Publication - Strategy/plan

Draft Sectoral Marine Plans for Offshore Renewable Energy in Scottish Waters - Environmental Report Appendix D: Draft Plan Options Assessment

Published: 25 Jul 2013
Part of:
Marine and fisheries
ISBN:
9781782567455

Appendix D to the SEA Environmental Report of the Draft Sectoral Marine Plans for Offshore Renewable Energy in Scottish Waters.

This appendix contains a Draft Plan Options Assessment.

87 page PDF

1.4 MB

87 page PDF

1.4 MB

Contents
Draft Sectoral Marine Plans for Offshore Renewable Energy in Scottish Waters - Environmental Report Appendix D: Draft Plan Options Assessment
2 Wave Draft Plan Options

87 page PDF

1.4 MB

2 Wave Draft Plan Options

WW1

SEA Topic

Summary of Key Baseline Evidence

Potential for effects

Characteristics

Mitigation available and potential residual effects

Biodiversity, Flora and Fauna

The Draft Plan Option is located in proximity to the Rinns of Islay SPA and SSSI (designated for a number of bird species including Chough, Greenland white-fronted goose and Whooper swan) and to the north west is the Oronsay and South Colonsay SPA and SSSI (with Corncrake and Chough qualifying features). The North Colonsay and Western Cliffs SPA is designated for breeding seabird assemblage (with Chough, Kittiwake and Guillemot present).

The Draft Plan Option is also located south of the Skye to Mull MPA search area, considered to be important for its geodiversity and the presence of Basking shark and Minke whale species.

The seabird maps presented in the baseline indicates a potential vulnerability for diving birds in both winter and breeding seasons, although this vulnerability is slightly higher in the winter season. However, this vulnerability may differ for individual species.

The south east of Islay contains the South-East Islay Skerries SAC designated for Common seals. The identification of several Seal haul out areas located in Islay and Colonsay and high Seal densities in the vicinity of these areas demonstrates Grey seal interests in this region.

The available distribution and sighting data also indicates that likely to be Cetacean, elasmobranch and fish ( i.e. Basking shark, Atlantic salmon, etc.) interests in the region. While the Draft Plan Option is located some distance south of the Basking shark and Common skate 'hotspots' located in the vicinity of Tiree, Coll and Mull, these species and other elasmobranch species may be encountered within the Draft Plan Option.

The area is known to be used by fish species, including diadromous species, such as Atlantic salmon, and others including Sea trout and many commercially caught species. The region also contains important nursery grounds for several commercially important species of fish.

The seabed in the vicinity of the Draft Plan Option is composed of predominantly coarse sediments ( i.e. sandy gravels and gravelly sands) with coarser materials to the west of Islay and south of the option area. These habitats are likely to contain species used to strong wave and tidal movements.

Potential vulnerabilities for collision and displacement of diving birds were identified in relation to the Draft Plan Option, particularly during winter periods. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables.

Given the likely presence of marine mammals and fish, particularly elasmobranchs such as Basking sharks, Cetaceans and Seals in the vicinity of the Draft Plan Option, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). While avoidance may be possible for some species in some circumstances, there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

The review of current wave technologies identified potential effects from EMF on fish and elasmobranchs although research into the magnitude of effects demonstrates that this is uncertain.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area.

The potential remains for collision and displacement of diving birds with the presence of wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain. The western edge of the plan area in particular may coincide with areas used by Basking sharks and Cetaceans.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there would be no significant impacts on diving birds and mobile marine species in the vicinity as a result of collision with wave devices.

Further research into the potential collision, displacement and the effects on cetaceans, seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

Development to the west of the Draft Plan Option and further away from Islay may reduce the potential for impacts on bird species.

The potential for effects from grid infrastructure could be avoided if supporting onshore/offshore connections were located away from sensitive areas, such as Islay.

Population and Human Health

The waters to west and north west of Islay are used for a number of industry and recreational activities including fishing, recreational sea angling, light recreational cruising, surfing and diving.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan area were classified as being of good status under the WFD in 2011.

There are two designated shellfish waters within the vicinity of the Draft Plan Option off Jurra and Colonsay.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur.

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

Broadly stable coastal areas with small sections of the coastline identified as potentially being vulnerable to erosion/accretion ( e.g. sheltered beaches and bays on Islay, southern side of Colonsay and south west areas of Mull), particularly during storm events.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics although much of the coastline near the Draft Plan Option is broadly stable.

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed in the vicinity of the Draft Plan Option is composed of predominantly coarse sediments ( i.e. sandy gravels and gravelly sands) with coarser materials to the west of Islay and south of the option area.

The area has moderate wave and tidal energy, a high tidal energy zone is located immediately south of the area, to the west and south west of Islay.

While there are largely coarse sediments in the area, some sediment disturbance and loss of seabed habitat is still likely during site preparation and placement of device foundations. The scale of such disturbance will depend on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site. This could lead to general effects such as scour and abrasion at the site, and deposition of sediments in nearby areas. This may be of particular concern for sites near to relatively sheltered areas, and areas of high accretion ( e.g. sheltered bays along the north coast of Islay) However, these systems are likely to be complex, and as such, the potential for impacts is likely to be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes, particularly given the proximity to sensitive coastal areas on Islay.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used.

Historic Environment

There are a number of marine and coastal wreck sites within this region, including small clusters of wreck sites located near the west coast of Tiree, the west and south coasts of Islay, and along the southern and south east coasts of Kintyre.

Significant sections of coastal and marine areas in Tiree, Colonsay, Islay and Kintyre have been identified as being of potential interest for submerged archaeology.

Nearby coastal areas also contain a wide range of historical features located either on the shoreline or which are of coastal relevance ( e.g. designated lighthouses, listed buildings, and scheduled monuments such as fortifications and early church sites). Colonsay and Oronsay in particular have range of sensitive coastal sites including the Nave Island Chapel and Viking House.

The proximity of the Draft Plan Option to the coastline means there is the potential for effects on the setting of coastal assets ( e.g. Iona Abbey, the numerous scheduled forts along the coast in Western Islay, Dhu Heartach Lighthouse and Nave Island Chapel) particularly from devices with large visible above water components

Potential for impacts on historic wreck sites in the vicinity of the developments from their installation and operation.

The likely presence of submerged archaeology means that there is potential for direct effects on any remains. However, development which includes archaeological survey may also have some positive effects by contributing to knowledge/understanding about the marine historic environment.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and long-term; for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of sites and seek to mitigate accordingly.

Landscape / Seascape

The Draft Plan Option is in proximity to the Islay coast, with the south eastern part of the Draft Plan Option particularly near to a local landscape designation area located in the north west of Islay.

The islands of Oronsay, Colonsay and Mull have a number of landscape designations and areas of wild land along the coast that may have views to the Draft Plan Option.

The Jura NSA might be a relevant consideration for development within the Draft Plan Option.

Given the proximity of the Draft Plan Option to the Islay coast in particular, there is potential for visual effects from wave devices and supporting infrastructure on the local designations and areas of wild land.

The majority of the wave energy device and its supporting infrastructure will likely be below the water surface, and as a result, visual impacts may be minimised.

Visibility may be greater during construction periods rather than operation, depending on the technologies used. It is likely that construction / maintenance works and navigational aids ( e.g. marker buoys, lighting) will have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the option area.

Devices and, in particular, supporting infrastructure, within the wave option may be visible from the mainland which includes areas designated for their landscape importance and areas considered as wild land.

However, as the majority of the device infrastructure will be below the surface, the significance of effects may be lower than for other technologies ( e.g. wind). Impacts will also therefore be more likely during construction / maintenance than the operational phase.

The Draft Plan Option would alter the current seascape but the significance of this effect can depend on the technology used and the type of visual receptor ( e.g. human or designation). Residual visual effects for some technologies could be minimal once constructed.

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts could be greater for offshore receptors, such as recreational sea users, as their proximity to devices would be greater than onshore receptors.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects, however visual impacts to onshore receptors could potentially be limited by construction further from the mainland, in particular the east of the Draft Plan Option.

Impacts to the landscape and seascape character of Islay, Oronsay and Colonsay would also need to form part of project level assessments.

Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.

WW2

SEA Topic

Summary of Key Baseline Evidence

Potential for effects

Characteristics

Mitigation available and potential residual effects

Biodiversity, Flora and Fauna

The Draft Plan Option is located close to numerous designated areas, including Oronsay and South Colonsay SPA (with Corncrake and Chough qualifying features), North Colonsay and Western Cliffs SPA (designated for breeding seabird assemblage including Chough, Kittiwake and Guillemot) and the Treshnish Isles SPA, SAC and SSSI (designated for Storm petrel, Greenland barnacle goose, reefs and Grey Seals amongst others).The Cnuic agus Cladach Mhuile SPA and the Jura, Scarba and the Garvellachs SPA (Slightly further to the east) are designated for Golden eagle.

The Draft Plan Option is also partly located within the Skye to Mull MPA search area. This area is considered important for its geodiversity and the presence of Basking shark and Minke whale.

The seabird maps presented in the baseline indicate potential collision vulnerability for diving birds in breeding periods. However, this vulnerability may differ for individual species.

The presence of several Seal haul out areas near to WW2 on Mull and to the north on Coll confirms Seal density information showing that this is an important area for marine mammals, particularly Common seals. While distribution data indicates that low Cetacean movements and relatively few sighting of Basking sharks near the Draft Plan Option, the area is considered likely to be frequented by both, particularly Basking sharks given the proximity to a 'hotspot' identified to the north around Mull and Tiree. Other elasmobranchs are also known to use this area.

The area is used by a range of fish species, including diadromous species such as Atlantic salmon, and others including Sea trout and many commercially caught species. The region also contains important nursery grounds for several commercially important species of fish.

Benthic habitats in the region are largely coarse sediments ( e.g. sands and gravelly sands) and may be susceptible to hydrodynamic change. These habitats are likely to contain species used to strong wave movements.

Potential vulnerabilities for collision and displacement of diving birds was identified in relation to the Draft Plan Option, particularly for collision impacts in breeding periods. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables. For example, above water infrastructure may not be sufficiently great to significantly impact on Golden eagles.

Given the likely presence of marine mammals and fish, particularly elasmobranchs such as Basking sharks and Common skate, Cetaceans and Seals in the vicinity of the Draft Plan Option, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). However, avoidance may be possible for some species in some circumstances, and there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

The review of current wave technologies identified potential effects from EMF on fish and elasmobranchs although research into the magnitude of effects demonstrates that this is uncertain.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area.

The potential remains for collision and displacement of diving birds with the presence of with wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain. The Draft Plan Option may coincide with areas used by Basking sharks, Common skate, Seals and Cetaceans.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there will be no significant impacts on diving birds and mobile species in the vicinity as a result of collision with wave devices. The result of monitoring of wave projects currently in the application process has the potential to help provide greater certainty on the scale of these effects.

Further research into the potential collision, displacement and the effects on Cetaceans, Seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

The potential for effects from grid infrastructure could be avoided if supporting onshore/offshore grid connections were located away from sensitive areas, such as Mull and Iona.

It is recommended that the boundary of the Draft Plan Option is kept under review as part ascertaining whether the overlap with the Skye to Mull MPA search area will remain and would lead to adverse effects, or whether co-location is possible. Projects will need to demonstrate through the EIA process that they are compatible with the conservation objectives of the MPA.

Population and Human Health

The waters to the south west of Mull and Iona are used for a number of industry and recreational activities including fishing, recreational sea angling and medium recreational cruising.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan area were classified as being of good status under the WFD in 2011.

There are a number of designated shellfish waters within the vicinity of the Draft Plan Option around the isle of Mull.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur.

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

Broadly stable coastal areas with small sections of the coastline identified as potentially being vulnerable to erosion/accretion ( e.g. sheltered beaches and bays on the southern side of Colonsay, and south and south west coasts of Mull), particularly during storm events.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics although much of the coastline near the Draft Plan Option is broadly stable.

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed in the vicinity of the Draft Plan Option is composed of predominantly coarse sediments ( i.e. sands and gravelly sands) and seabed depth can range up to 80m.

The region has moderate wave and low tidal resources across much of the Draft Plan Option.

While there are largely coarse sediments in the area, some sediment disturbance and loss of seabed habitat is still likely during site preparation and placement of device foundations. The scale of such disturbance is likely dependent on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site. This could lead to general effects such as scour and abrasion at the site, and deposition of sediments in nearby areas. The potential for increased coastal erosion of deposition in surrounding areas due to the presence of devices has also been identified. However, these systems are likely to be complex, and as such, the potential for impacts is likely to be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used.

Historic Environment

There are a number of marine and coastal wreck sites within this region, including small clusters of wreck sites located near the west coast of Tiree, the west and south coasts of Islay, and along the west coast of Mull.

Significant sections of coastal and marine areas in Tiree, Colonsay, Mull and Islay have been identified as being of potential interest for submerged archaeology.

Nearby coastal areas also contain a wide range of historical assets located either on the shoreline or which are of coastal relevance ( e.g. designated sites such as lighthouses, listed buildings, and scheduled monuments including fortifications, early church sites). In particular the boundaries of the Draft Plan Option fall close to A-listed Dhu Heartach Lighthouse, and a range of historic environment features on Iona and Ross of Mull.

The historic Iona Abbey dates from AD 563 and is one of Scotland's most sacred religious sites.

The proximity of the Draft Plan Option to the coastline means there is the potential for impacts on the setting of historic environment assets ( e.g. Iona Abbey and Dhu Heartach Lighthouse).

Potential for impacts on historic wreck sites in the vicinity of the developments from their installation and operation.

The likely presence of submerged archaeology means that there is potential for direct effects on any remains. However, development which includes archaeological survey may also have some positive effects by contributing to knowledge/understanding about the marine historic environment.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and last for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of sites and seek to mitigate accordingly.

Given the importance of Iona Abbey and potential impacts on the setting of cultural assets any development in this area should only be developed where significant effects can be demonstrated to be are avoided.

Landscape / Seascape

The Draft Plan Option is located in proximity to the Mull coast, much of which is covered by a local landscape designation. The northern and western part of this area may be particularly visible from the Mull and Iona coastline, the northern edge of the site may be seen from areas within the Loch na Keal NSA, and the western part from Colonsay.

Much of the southern edge of Mull is designated as wild land and the setting of Iona is considered to be important for Christian cultural heritage features.

Given the proximity of the Draft Plan Option to Mull coast in particular, there is potential for visual effects on the local designations, the NSA and areas of wild land across Mull and Iona.

The majority of the device and supporting infrastructure will be submerged, and as a result, visual impacts may be minimised.

Visibility may be greater during construction periods than during operation, depending on the technologies used. It is likely that construction / maintenance works and navigational aids ( e.g. marker buoys, lighting) will have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the option area.

Devices and, in particular, supporting infrastructure within the wave option may be visible from the islands which includes areas designated for their landscape importance and areas considered as wild land.

However, as the majority of the device infrastructure will below the water surface the significance of effects may be lower than for other technologies ( e.g. wind). Impacts will also therefore be more likely during construction than the operational phase.

The Draft Plan Option would alter the current seascape but the significance of this effect can depend on the technology used. Residual visual effects for some technologies could be minimal once constructed.

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts could be greater for offshore receptors, such as recreational sea users as their proximity to devices would be greater than onshore receptors.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects. However visual impacts to onshore receptors could potentially be limited by construction further from the mainland, in particular the east of the Draft Plan Option.

Impacts to the landscape and seascape character of Mull, Iona, and potentially Colonsay, would also need to form part of project level assessments.

Given the high quality landscape and areas of importance for the setting of cultural assets any development in this area should only be undertaken where significant effects can be avoided. Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.

WW3

SEA Topic

Summary of Key Baseline Evidence

Potential for effects

Characteristics

Mitigation available and potential residual effects

Biodiversity, Flora and Fauna

The Tiree Wetlands and Coast SPA, and Tiree, Coll and Sleibhtean agus Cladach Thiriodh SPAs are located close to the Draft Plan Option with features including Corncrake, Oystercatcher, Polver and Geese, amongst others. Other SACs in the vicinity of the site are designated for dune habitats, whilst the Treshnish Isles SAC is designated for Grey seals. The south east of the Draft Plan Option overlaps with the Stanton Banks marine SAC which is designated for reef, which could have diverse benthic habitats that may be susceptible to change. IBAs have also been identified on many islands within this region.

The Draft Plan Option is also located within the Skye to Mull MPA. This area is considered important for its geodiversity and the presence of Basking shark and Minke whale.

The seabird maps presented in the baseline indicate that diving birds may be vulnerable to collision during the winter season in particular. However, this vulnerability may differ for individual species.

Distribution data presented in the baseline indicates that Cetaceans are likely to be present within the region and the Draft Plan Option is located near to Basking shark and Common skate 'hotspots' located near to Tiree and Coll, and numerous sightings in the vicinity of WW3 indicates the presence of this species in this area. Other elasmobranchs are also known to use these waters. Seal survey data and the presence of Seal haul out areas around Tiree, Coll and Mull indicates this is a well-used area for marine mammals, particularly Grey seals.

The area is known to be used by fish species, including diadromous species, such as Atlantic salmon, and others including Sea trout and many commercially caught species. The region also contains important nursery grounds for several commercially important species of fish.

Benthic habitats in the region are largely shallow and shelf subtidal coarse sediments ( e.g. sands, gravelly sands, gravels, etc.) and may be susceptible to hydrodynamic change. These habitats are likely to contain species used to strong wave and tidal movements.

Potential vulnerabilities for collision and displacement of diving birds has been identified in relation to the Draft Plan Option, particularly in winter periods. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables.

Seals and Basking sharks are likely to be present within the Draft Plan Option and could be potentially affected. Given the likely presence of marine mammals and fish, particularly elasmobranchs such as Basking sharks, Cetaceans and Seals in the vicinity of the Draft Plan Option, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). While avoidance may be possible for some species in some circumstances, there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

The review of current wave technologies identified potential effects from EMF on fish and elasmobranchs although research into the magnitude of effects demonstrates that this is uncertain.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area.

The potential remains for collision and displacement of diving birds with the presence of wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there would be no significant impacts on diving birds and mobile marine species in the vicinity as a result of collision with wave devices.

Further research into the potential collision, displacement and the effects on Cetaceans, Seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

Development to the west of the Draft Plan Option and further away from Islay may reduce the potential for impacts on bird species.

The potential for effects from grid infrastructure could be avoided if supporting onshore/offshore connections were located away from sensitive areas, such as Tiree.

It is recommended that the boundary of the Draft Plan Option is kept under review as part ascertaining whether the overlap with the Skye to Mull MPA search area will remain and would lead to adverse effects, or whether co-location is possible. Particular issues to consider would be the collision risk with priority marine features. Projects will need to demonstrate through the EIA process that they are compatible with the conservation objectives of the MPA.

Population and Human Health

The waters to the south west of Tiree are used for a number of industry and recreational activities including fishing, recreational sea angling, light recreational cruising, surfing and diving.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan are, were classified as being of good status under the WFD in 2011.

There are some designated shellfish waters within the vicinity of the Draft Plan Option around the Isle of Mull.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur.

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

The draft plan area is located near to the coastline of Tiree, consisting of broadly stable rock coasts and small sheltered beaches. The coastline is considered broadly stable, although the sandy sections of the coastline have been identified as being potentially vulnerable to erosion/accretion ( e.g. particularly those on the southwest and west coasts).

Accretion has been identified in several Bays located in the east and north east of the Tiree.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics although much of the coastline near the Draft Plan Option is broadly stable.

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed in the vicinity of the Draft Plan Option is composed of predominantly coarse sediments ( i.e. sandy gravels, gravelly sands and gravels).

The region has moderate wave and low tidal resources across much of the Draft Plan Option, with stronger tidal areas to the west of Tiree, and immediately north of the Draft Plan Option.

While there are largely coarse sediments in the area, some sediment disturbance and loss of seabed habitat is still likely during site preparation and placement of device foundations. The scale of such disturbance is likely dependent on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site. This could lead to general effects such as scour and abrasion at the site, and deposition of sediments in nearby areas. The potential for increased coastal erosion or deposition in surrounding areas due to the presence of devices and their foundations has also been identified ( e.g. southern coastline of Tiree). However, these systems are likely to be complex, and as such, the potential for impacts is likely to be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used

Historic Environment

There are a number of marine and coastal wreck sites within this region, including small clusters of wreck sites located near the west coast of Tiree.

Coastal areas also contain a wide range of historical features located either on the shoreline or which are of coastal relevance ( e.g. lighthouses, and scheduled monuments such as fortifications and early church sites). Significant sections of coastal and marine areas in Tiree have been identified as being of potential interest for submerged archaeology.

Adoption of sites in the Draft Plan Option may have the potential to impact on the setting of the Category A listed Skerryvore Lighthouse.

Furthermore, the close proximity of the site footprint to the southern tip of Tiree would suggest potential setting impacts on a number of coastal scheduled fortifications and early church sites.

Potential for impacts on historic wreck sites from installation and operation of these sites.

The likely presence of submerged archaeology means that there is potential for direct effects on any remains. However, development which includes archaeological survey may also have some positive effects by contributing to knowledge/understanding about the marine historic environment.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and last for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of historic sites and seek to mitigate accordingly.

Landscape / Seascape

The Draft Plan Option is in proximity to south and west of the island of Tiree, much of which is covered by local landscape designations. The north west part of the Draft Plan Option may be visible from the coastline, and the eastern edge of the option may be visible from areas within the Loch na Keal NSA.

The coastline of Tiree is not identified as an area of wild land, although this may potentially indicate that there could be more receptors to offshore development in this region ( e.g. recreational sea users).

Given the proximity of the Draft Plan Option to the Tiree coast there is potential for visual effects on areas with local landscape designations..

The majority of the device and supporting infrastructure will be below the water surface, and as a result, visual impacts may be minimised.

Visibility may be greater during construction periods than operation, although this will likely depend on the technologies used. It is likely that construction works and navigational aids ( e.g. marker buoys, lighting) will have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the option area.

Devices, and in particular supporting infrastructure, within the wave option may be visible from Tiree which includes areas designated for their landscape importance.

However, as the majority of the device infrastructure will be below the water surface, the significance of effects may be lower than for wind energy technologies. Impacts are also more likely to occur during construction and maintenance than in the operational phase.

The Draft Plan Option would alter the current seascape but the significance of this effect can depend on the technology used. Residual visual effects for some technologies could be minimal once constructed.

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts are likely to be greater for offshore receptors, such as recreational sea users.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects. However visual impacts to onshore receptors could potentially be limited by construction further from the mainland, in particular the west of the Draft Plan Option.

Impacts to the landscape and seascape character of Tiree would also need to form part of project level assessments.

Given the high quality landscape present in this region, any development in this area should only be undertaken where significant effects can be avoided. Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.

WW4

SEA Topic

Summary of Key Baseline Evidence

Potential for Effects

Characteristics

Mitigation Available and Potential Residual Effects

Biodiversity, Flora and Fauna

The north west of the Draft Plan Option overlaps with the Mingulay and Berneray SPA and SSSI which has a number of seabird assemblage interests (including Fulmar, Puffin, Kittiwake, Razorbill and Guillemot). To the east of WW4 is the East Mingulay marine SAC (designated for reefs), and Small Seal islands SSSI (Grey seal interests) and the Sound of Barra p SAC (marine habitat and Common seal interests) are located to the north west of the site.

The Draft Plan Option is located to the east of the Skye to Mull MPA search area, being considered for its importance for its geodiversity and the presence of Basking shark and Minke whale.

Seabird maps presented in the baseline indicate there may be potential collision vulnerability for diving birds during the breeding season, particularly in the northern part of the Draft Plan Option. However, this vulnerability may differ for individual species.

The available distribution and sighting data also indicates that there are likely Cetaceans present in the vicinity of the Draft Plan Option. Basking shark sightings have been recorded amongst the southern islands of the outer Hebrides, with the area to the east of Mingulay and Barra considered to be a Basking shark 'hotspot'. Other elasmobranchs are also known to use these waters. Seal density mapping, the presence of seal haul outs and the proximity of the Draft Plan Option to an SAC designated for Common seal interests, illustrates the importance of the area for these Seals.

The area is known to be used by fish species, including diadromous species, such as Atlantic salmon, and others including Sea trout and many commercially caught species. The region also contains important nursery grounds for several commercially important species of fish.

Benthic habitats in the region are largely coarse sediments ( e.g. sands, gravelly sands, gravels, etc.) becoming finer northwards ( e.g. muddy sandy gravel) and with rocky outcrops covering much of the remainder of the region. These sediment-based habitats may be susceptible to hydrodynamic change, and likely contain species used to strong wave movements.

Potential vulnerabilities for collision and displacement of diving birds was identified in relation to the Draft Plan Option, particularly for collision potential during breeding periods and in areas closer to the coastline. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables.

Given the likely presence of marine mammals and fish, particularly Cetaceans and Seals in the vicinity of the Draft Plan Option, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). However, avoidance may be possible for some species in some circumstances, and there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area. However, location of developments in rocky areas could limit these effects, but this will likely be influenced by factors such as the specific locations selected by developers and the engineering requirements of wave energy technologies.

The potential remains for collision and displacement of diving birds with the presence of wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there would be no significant impacts on diving birds and mobile marine species in the vicinity as a result of collision with wave devices.

Further research into the potential collision, displacement and the effects on Cetaceans, Seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

Given proximity of the draft plan area to several important areas for birds, development to the south of the Draft Plan Option is would be preferred.

It is recommended that the boundary of the Draft Plan Option is kept under review as part ascertaining whether the overlap with the Mingulay and Berneray SPA would lead to adverse effects or whether co-location is possible. Project level HRA must demonstrate development does not adversely affect the integrity of the SPA.

The potential for effects from grid infrastructure could be avoided if supporting onshore/offshore connections were located away from sensitive areas, such as Barra and Mingulay.

Population and Human Health

The waters to the west of Barra and Mingulay are used for a number of industry activities including fishing, recreational sea angling and light recreational cruising.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan area were classified as being of either good or high status under the WFD in 2011.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

The western beaches of the Outer Hebridean Islands are dominated by wind and wave action. The western coasts of the southern isles ( e.g. Barra, Sandray, and Mingulay) have broadly rocky coastal areas with several self-contained pocket beaches, particularly along the western coastline of Barra.

Wave erosion of the machair edge has been observed in sections of the west coast, and storm damage of the shingle edge has been observed on Vatersay. As such, some sections of the coastline have been identified as potentially being vulnerable to erosion/accretion, particularly during storm events.

The potential for increases in storm events and rising sea levels have been identified, due to the effects of climate change.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics particularly where developments are located near to potentially vulnerable coastlines.

Given the high levels of wave action on the west coast of the Outer Hebrides and the erosion issues associated with this, developments may in some instances aid the protection of vulnerable coastlines

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed in the vicinity of the Draft Plan Option is of variable depth (ranging from 20 - 120m) and consists mainly of rock outcrops to the immediate west of Barra. Sandy and gravelly sediments are located further west and muddy sandy sediments in the south east portion of the option area, to the south and south east of Mingulay.

The Draft Plan Option has moderate wave and tidal resources, with extensive areas of stronger wave energy further to the west, north west and south west of Mingulay.

While there are largely coarse sediments in much of the area, some sediment disturbance and loss of seabed habitat is still likely during site preparation and placement of device foundations. The scale of such disturbance is likely dependent on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

As such significant increases in turbidity may occur for developments within the south east portion of the Draft Plan Option.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site, with potential general impacts such as scour, deposition and abrasion in the area and related impacts to vulnerable coastlines ( e.g. Barra, Mingulay). However, these systems are likely to be complex, and as such, the potential for impacts will be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes, particularly given the sensitive coastlines of the southern islands within the Outer Hebrides.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used

Historic Environment

There are a number of marine and coastal wreck sites in the Outer Hebrides, including several near Barra.

These coastal areas of these islands also contain a wide range of historical features located either on the shoreline or which are of coastal relevance ( e.g. Barra Head lighthouse and a cluster of coastal sites within the southern isles of the Outer Hebrides).

The proximity of the site to the southern tip of Barra would suggest there is potential for effects on the setting of a number of sites, including coastal scheduled monuments and Barra Head Lighthouse. This is particularly the case where devices have large visible above water components.

There may be the potential for impacts on historic wreck sites from installation and operation of these sites.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and last for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of sites identified in the baseline and seek to mitigate accordingly.

Landscape / Seascape

The Draft Plan Option is in located near to the coastline of the Southern islands in the Outer Hebrides, many of which are considered important for their natural environmental value and landscape features. The Draft Plan Option may be visible from South Uist Machair NSA.

Many of the coastlines in this region are identified for their wildness value.

Given the proximity of the Draft Plan Option to the islands there is potential for visual effects on the local environment and areas of wild land.

There is the potential for changes to the seascape character of the area. However, as the majority of the wave devices and supporting infrastructure will be below the water surface, visual impacts may be reduced. As such, visibility may be greater during construction and maintenance periods than during operation, although this will depend on the technologies used.

It is likely that construction works and navigational aids ( e.g. marker buoys, lighting) will have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the option area.

Wave energy devices, and in particular any supporting infrastructure, within the Draft Plan Option may be visible from nearby islands including areas designated for their landscape importance and/or for their wildness.

However, as the majority of the device infrastructure will be below the water surface, the significance of effects may be lower than for wind technologies. Impacts will also be more likely during construction and maintenance phase, rather than during operation.

Development in the plan option would likely alter the current seascape and, therefore, potentially affect its character. However, this will depend on the technology used, and the number of human receptors in this remote area may be few. For example, residual visual effects for some technologies could be minimal once constructed.

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts could be greater for offshore receptors, such as recreational sea users.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects. However visual impacts to onshore receptors could potentially be limited by construction further from the mainland, in particular the west of the Draft Plan Option.

Impacts to the landscape and seascape character would also need to form part of project level assessments.

Given the high quality landscape identified in this area, any development should only be undertaken where significant effects can be avoided. Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.

Development of the southern and western parts of the plan option could potentially reduce visual and landscape/seascape impacts.

WNW1

SEA Topic

Summary of Key Baseline Evidence

Potential for effects

Characteristics

Mitigation available and potential residual effects

Biodiversity, Flora and Fauna

The Draft Plan Option covers a large area of marine waters off Scotland's Western Isles, and is located near to a wide range of designated sites. Just west of the South eastern tip of the Draft Plan Option is St Kilda SPA and SAC designated for coastal habitats and seabird assemblages (including Fulmar, Puffin, Kittiwake, Razorbill, Skua and Guillemot). Sites to the east include the North Harris SAC and SSSI and North Harris Mountains SPA (designated for habitat and Golden eagle interests), and North Harris and Langavat SACs (for Atlantic salmon interests) amongst others. Several IBAs have also been identified in the vicinity of the Draft Plan Option.

To the south or south east of the Draft Plan Option is the Monach Isles SPA and SAC (designated for dune habitats, Grey Seal, Common tern, Little tern and Greenland Barnacle goose) and several SPAs and SSSI including the North Uist Machair and Islands SPA (designated for Ringed plover, Redshank, Corncrake, Dunlin, Oystercatcher, Purple sandpiper, Turnstone, and Greenland Barnacle goose) and Small Seal Islands SSSI (with Grey seal interests).

The Flannan Isles SPA is located within the Draft Plan Option, and is designated for similar bird assemblages to other nearby SPAs.

Potential collision vulnerability for diving birds from wave energy was identified in the winter season in the south east corner of the Draft Plan Option, and during the breeding season, particularly in the south and north east parts of the Draft Plan Option. However, this vulnerability may differ for individual species.

The Cetacean distribution maps indicate that Cetaceans are likely to be present around the Draft Plan Option.

Basking shark sightings have been recorded along the western coast of Lewis and Harris, including several in offshore areas within WNW1, indicating the potential for encounters in this vicinity. Other elasmobranchs are also known to use this area.

Seal density mapping and the presence of seal haul out areas near to WNW1 illustrates the importance of this area for Grey seals.

The north east part of the Draft Plan Option is located close to the top of the Eye Peninsula to Butt of Lewis MPA search area, proposed for Rissos dolphin, white-beaked dolphin, and sand eels. To the west of WNW1 are two further MPA search areas, proposed for seabed and geodiversity features.

The area is known to be used by fish species, including diadromous species, such as Atlantic salmon, and others including Sea trout and many commercially caught species. The region also contains important nursery grounds for several commercially important species of fish.

Seabed sediments are described as rocky with areas of coarse sediments. These benthic habitats are likely to contain species used to strong tidal movements and currents, such as the kelp forests within the Draft Plan Option which provides important services for marine fauna and coastal protection.

Potential vulnerabilities for collision and displacement of diving birds was identified in relation to the Draft Plan Option. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables.

Given the likely presence of marine mammals and fish, particularly Cetaceans and Seals in this region, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). While avoidance may be possible for some species in some circumstances, there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

The review of current wave technologies identified potential effects from EMF on fish and elasmobranchs although research into the magnitude of effects demonstrates that this is uncertain.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments. As a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area. However, location of developments in rocky areas could limit these effects, but this will likely be influenced by factors such as the specific locations selected by developers and the engineering requirements of wave energy technologies.

Potential impacts to MPA search area sites noted for geodiversity interests from sediment movements are not considered to be significant due to distance between these areas and the Draft Plan Option.

The potential remains for collision and displacement of diving birds with the presence of wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain. The western edge of the plan area in particular may coincide with areas used by Basking sharks and Cetaceans.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Impacts to seabed geodiversity will likely be limited to the direct effects of installation of devices. Impacts from piling effects could be greater than for the use of gravity based devices.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there would be no significant impacts on diving birds and mobile marine species in the vicinity as a result of collision with wave devices. The results of monitoring from projects currently in the application process have the potential to help provide greater certainty on the scale of these effects.

Further research into the potential collision, displacement and the effects on Cetaceans, Seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

Given proximity of the draft plan area to important areas for birds, development to the west and north west of the site is recommended.

It is recommended that the boundary of the Draft Plan Option is kept under review as part ascertaining whether the fact that the Flannan Isles SPA are contained within the Draft Plan Option would lead to adverse effects on the integrity of the designation or whether co-location is possible. Furthermore the distance between the boundary of the Draft Plan Option and the St Kilda SPA and SAC is recommended if adverse effects on its integrity are determined. Project level HRA must demonstrate development does not adversely affect the integrity of the SAC and SPA.

Furthermore, it is recommended that the boundary of the Draft Plan Option is kept under review as part ascertaining whether the overlap with the Eye Peninsula to Butt of Lewis MPA search area will remain and would lead to adverse effects, or whether co-location is possible. Projects will need to demonstrate through the EIA process that they are compatible with the conservation objectives of the MPA.

Potential effects of supporting onshore/offshore grid connections will need to be considered to avoid effects on areas on the western isles if the grid connection is to the islands.

Population and Human Health

The waters and coastal areas to the west of Lewis and the Sound of Harris are used for a number of industry and recreational activities including fishing, recreational sea angling, recreational cruising, sailing and surfing.

There are a number of well-established sailing and marine tourism routes through the Draft Plan Option to and from Saint Kilda and locations along the Hebrides including those within the Sound of Harris, and the north west coast of Lewis.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan area were classified as being of high status under the WFD in 2011.

There is one area defined as shellfish waters within the vicinity of the Draft Plan Option off the northern coast of Lewis.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur.

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

The western coastline of the outer Hebrides is dominated by wind and wave action. The western coast of the Lewis is largely stable and rocky, while north Uist, immediately south east of the draft plan area, contains several sandy beaches that have been identified as being potentially vulnerable to erosion/accretion, particularly during storm events.

Wave erosion of the western Lewis coastline ( e.g. soft till cliffs) is mainly confined to storm conditions, although there is slight erosion of the coastal edge at several locations and several areas of erosion and accretion have been identified along the coastline ( e.g. Luskamol, Sound of Harris, North Uist. And sheltered bays along the western Lewis coast).

The potential for increases in storm events and rising sea levels have been identified, due to the effects of climate change.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics particularly where developments are located near to potentially vulnerable coastlines.

Given the high levels of wave action on the west coast of the Outer Hebrides and the erosion issues associated with this, developments may in some instances aid the protection of vulnerable coastlines

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed across this large Draft Plan Option area is of widely varying depth (ranging from 30 - 140m) and consists mainly of sandy and gravelly sediments, with large areas of undifferentiated solid rock outcrops to the west of Lewis and to the north west of Uist.

The Draft Plan Option has strong wave and low tidal resources, increasing in a westerly direction from Lewis and Harris.

Some seabed disturbance and loss of habitat is likely with the site preparation and placement of device foundations. The scale of such disturbance is likely dependent on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

As such significant increases in turbidity are unlikely given the largely coarse sediments and rock seabed formations within the option area.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site, with potential general impacts such as scour, deposition and abrasion in the area and the potential for related impacts to vulnerable coastlines ( e.g. west coast of Lewis and Harris). However, these systems are likely to be complex, and as such, the potential for impacts will be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes, particularly given the important coastal areas on the west side of Lewis and Harris.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used

Historic Environment

There are a number of marine and coastal wreck sites in the Outer Hebrides, including several near Barra.

The Draft Plan Option sits very close to a number of sensitive coastal sites in the Isle of Lewis, Harris and North Uist. These sites include both scheduled and unscheduled monuments such as duns, cairns and forts, and a range of listed buildings located along the coastline. A particularly high density of sites has been identified along the north west coast of the Lewis.

The eastern most portion of the Draft Plan Option is located adjacent to the St Kilda World Heritage Site.

The coastal areas of these islands also contain a wide range of historical features located either at the shoreline or are of coastal relevance ( i.e. Barra Head lighthouse and a cluster of coastal sites within the southern isles of the Outer Hebrides).

There may be the potential for impacts on historic wreck sites from installation and operation.

As the draft option area sits very close to a number of sensitive coastal assets on Lewis, Harris and North Uist, there is potential for significant impacts on their settings. This is particularly the case where devices employed have large visible above water components.

While there is some potential for developments to have an adverse impact on the setting of the St Kilda World Heritage Site, it is likely that developments would be located some distance from the site.

Potential setting impacts on a number of sites, including coastal scheduled duns and Barra Head Lighthouse, and particularly for those devices with large visible above water components.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and last for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of sites including the St Kilda WHS and seek to mitigate accordingly.

Landscape / Seascape

The Draft Plan Option covers a large area, with its eastern boundary located in close proximity to the coastline of the Western Isles, particularly Lewis and Harris. Much of this coastline is considered important for its natural environment and landscape features.

Much of the eastern perimeter of the Draft Plan Option is bordered by the South Lewis, Harris and North Uist NSA, and much of this area is identified as possessing high wildness value.

Given the proximity of the Draft Plan Option to the islands there is potential for visual effects on the local environment, wild land and the NSA if development occurs within the eastern portion of the Draft Plan Option.

There is the potential for changes to the character of the seascape and potentially on the setting of the NSA.

The majority of the many wave device technologies and its supporting infrastructure will likely be below the water surface, and as a result, visual impacts may be minimised.

Visibility may be greater during construction and maintenance periods more so than during operation, although this will depend on the technologies used.

It is likely that construction works and navigational aids ( e.g. marker buoys, lighting) will have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the option area.

Wave energy devices, and in particular any supporting infrastructure, within the draft plan option may be visible from nearby islands including areas designated for their landscape importance and/or for their wildness

However, as the majority of the device infrastructure will be below the water surface, the significance of effects may be lower than for other technologies ( e.g. wind). Impacts will also be more likely during construction and maintenance phase, rather than during operation.

Development in the plan option would likely alter the current seascape and potentially affect its character. However, this will depend on the technology used, and the number of human receptors in this remote area may be few. For example, residual visual effects for some technologies could be minimal once constructed

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts could be greater for offshore receptors, such as recreational sea users.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects. However visual impacts to onshore receptors could potentially be limited by construction further from the Lewis and Harris coastlines, in particular, in the west of the Draft Plan Option.

Impacts to the landscape and seascape character would also need to form part of project level assessments. Given the high quality landscape identified in this area, any development should only be undertaken where significant effects can be avoided. Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.

Development of the western parts of the plan option could potentially reduce visual and landscape/seascape impacts.

WN1

SEA Topic

Summary of Key Baseline Evidence

Potential for effects

Characteristics

Mitigation available and potential residual effects

Biodiversity, Flora and Fauna

The Draft Plan Option is in close proximity to the North Sutherland Coast, and is located to the west of Thurso. There are a number of important designations in its vicinity, both on the Scottish mainland and in Orkney, including the Hoy SPA, Caithness and Sutherland Peatlands SPA, North Caithness Cliffs SPA, Caithness and Sutherland Peatlands SPA (all designated for their seabird assemblage interest including Fulmar, Skua, Puffin, Kittiwake, Razorbill, Guillemot, Red Throated Diver, and Cormorant) amongst others. North Caithness Cliffs SPA is additionally designated for Peregrine and the North Sutherland Coastal Islands SPA is designated for Greenland barnacle goose. North of the mainland and the plan option are Sule Skerry and Sule Stack SPAs, both designated for similar seabird species.

Other sites located in the vicinity of the Draft Plan Option include Hoy SAC (designated for its vegetated cliffs) and Invernaver SAC (for its dune habitats), Strathy Coast SSSI (for coastal and geological interests) and River Naver, Thurso and Borgie SACs (for Atlantic salmon and Freshwater pearl mussel interests). The option overlaps with Strathy Point SAC.

The baseline identifies potential some vulnerability of diving birds to collision with wave energy devices in breeding and winter season. However, this vulnerability may differ for individual species.

The Cetacean distribution map presented in the baseline indicates that Cetaceans may be present in the Draft Plan Option. Basking shark sightings have been recorded along the North Sutherland coast, including several within WN1, indicating the potential for encounters within this area. Other elasmobranch species are known to use these waters.

The Seal density maps and the presence of haul out sites to the west of WN1 and in the Pentland Firth, indicates the likely presence of Grey seals in the Draft Plan Option.

The area is known to be used by fish species, including diadromous species, such as Atlantic salmon, and others including Sea trout and many commercially caught species. The wider northern region also contains important nursery grounds for several commercially important species of fish.

The seabed off the North Sutherland Coast consists mainly of coarse sediments ( i.e. sandy gravels and gravelly sands). These benthic habitats are likely to contain species used to strong wave conditions.

Potential vulnerabilities for collision and displacement of diving birds were identified in relation to the Draft Plan Option in this area. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables.

Given the likely presence of marine mammals and fish, particularly Cetaceans and Seals in Scotland's northern waters, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). While avoidance may be possible for some species in some circumstances, there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

The review of current wave technologies identified potential effects from EMF on fish and elasmobranchs although research into the magnitude of effects demonstrates that this is uncertain.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area. While the potential for sediment movement from the installation of wave devices and their associated infrastructure has been identified, this will likely depend on the type of devices and installation technologies used.

The potential remains for collision and displacement of diving birds with the presence of wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain. The western edge of the plan area in particular may coincide with areas used by Basking sharks and Cetaceans.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there would be no significant impacts on diving birds and mobile marine species in the vicinity as a result of collision with wave devices. The results of monitoring from projects currently in the application process have the potential to help provide greater certainty on the scale of these effects.

Further research into the potential collision, displacement and the effects on Cetaceans, Seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

The potential for effects of supporting onshore/offshore grid connections will need to be considered to avoid effects on areas on sensitive coastal areas.

The potential for impacts on important coastal and reef habitats should be monitored.

It is recommended that the boundary of the Draft Plan Option is reviewed as part of ascertaining whether the overlap with the Strathy Point SAC would lead to adverse effects or whether co-location is possible. Project level HRA must demonstrate development does not adversely affect the integrity of the SAC.

Population and Human Health

The waters and coastal areas of the North Sutherland Coast are used for a number of industry and recreational activities including fishing, recreational sea angling, recreational cruising, bathing and surfing. Recreational vessels are known to travel along the Sutherland coast to the Pentland firth, and between Loch Eriboll and the Orkney Isles.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan area were classified as being of good status under the WFD in 2011.

There are designated shellfish waters along the Sutherland coast although these are not directly adjacent to the Draft Plan Option.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur.

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

The coastline between Duncansby Head and Cape Wrath comprises largely rocky coastlines with pocket sandy beaches, and intertidal sand flats near river mouths. As such, the soft parts of this coastline have been identified as being potentially vulnerable to erosion/accretion, with some erosion having been identified ( e.g. near to the Kyle of Tongue and the draft plan area). Little other continuous beach or coastal erosion is evident, other than under storm conditions. Some beach areas at the mouths of rivers have slight gains in material.

The potential for increases in storm events and rising sea levels have been identified, due to the effects of climate change.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics particularly where developments are located near to intertidal sand flats at river mouths, such as those found near the Kyle of Tongue

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed across the North Sutherland Coast and the Draft Plan Option is up to around 100m in depth, and consists mainly of coarse sediments ( i.e. sandy gravels and gravelly sands).

The coastline has generally moderate wave and tidal energies.

Some seabed disturbance and loss of habitat is likely with the site preparation and placement of device foundations. The scale of such disturbance is likely dependent on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

As such significant increases in turbidity are considered unlikely given the coarse sediments and rock seabed formations within the option area.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site, with potential general impacts such as scour, deposition and abrasion in the area and related impacts to vulnerable coastlines ( e.g. inlets such as the Kyle of Tongue). However, these systems are likely to be complex, and as such, the potential for impacts will be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used

Historic Environment

There are a number of marine and coastal wreck sites off the North Sutherland Coast, including several in or close to the Draft Plan Option.

There are a relatively low number of sensitive coastal historic environment assets located near the option area. The most notable is Borve Castle which is situated near Farr on the North Sutherland Coast.

Although there are a low number of sensitive coastal sites in this region, there is potential for significant impacts on the setting of assets which have been identified, particularly Borve Castle. Setting impacts will be most significant where the devices employed have large visible above water components.

There may be the potential for impacts on historic wreck sites from installation and operation of these sites.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and last for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of sites identified in the baseline and seek to mitigate accordingly.

Landscape / Seascape

The Draft Plan Option is located close the Kyle of Tongue NSA, and further afield the Hoy and West Mainland NSA on Orkney.

Large parts of the Hoy coastline have a high wildness level. The coastal edges of the North Sutherland coast have small sections of wild land. However the A836 cuts along the coastline of the mainland, limiting the area of wildness.

The Draft Plan Option could be visible from cliffs and the Kyle of Tongue NSA on the northern coast of the mainland. The presence of the coastal A836 could potentially increase visibility for onshore receptors.

There is the potential for changes to the character of the seascape and potentially on the setting of the NSA. However the majority of the device and supporting infrastructure will likely be below the water surface, and in such cases, visual impacts may be minimised.

Visibility effects may occur during construction and maintenance periods more so that during operation. It is likely that navigational aids ( e.g. marker buoys, lighting) will also have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the option area.

Wave devices, and in particular its supporting infrastructure, within the Draft Plan Option may be visible from the Scottish mainland which includes several areas designated for their landscape importance and their wildness.

However, as the majority of the device infrastructure for many wave technologies will be below the water surface, the significance of effects may be lower than for wind devices. Visual impacts will also be more likely during construction and maintenance phase than during operation.

The plan option could alter the current seascape and potentially affect its character. However, this will depend on the technology used and the number of receptors in this remote area may be few. Residual visual effects for some technologies could be minimal once constructed.

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts could be greater for offshore receptors, such as recreational sea users.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects. However visual impacts to onshore receptors could potentially be limited by construction further from the mainland, in particular the west of the Draft Plan Option.

Impacts to the landscape and seascape character would also need to form part of project level assessments. Given the high quality landscape identified in this area, any development should only be undertaken where significant effects can be avoided. Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.

WN2

SEA Topic

Summary of Key Baseline Evidence

Potential for effects

Characteristics

Mitigation available and potential residual effects

Biodiversity, Flora and Fauna

The Draft Plan Option covers a large section of the waters to the north west of the Orkney Isles. There are a number of important designations in the area, including coastal SPAs such as Hoy SPA and Marwick Head SPA with which it overlaps, Rousay SPA, West Westray SPA, Papa Westray (North Hill and Holm) SPA, Calf of Eday SPA, all designated amongst others for seabird assemblages (including Fulmar, Skua, Puffin, Kittiwake, Razorbill, Guillemot, Red Throated Diver, Cormorant, Gulls Tern, but also Peregrine). Between Orkney and Shetland lies Fair Isle SPA, which has been designated for similar bird species.

Orkney also contains the Sanday SAC (designated for sandflats, reefs and Common Seal), Faray and Holm of Faray SAC (designated for Grey Seal) and Stromness Heaths and Coast SAC (designated for its vegetated cliffs). The Draft Plan Option overlaps with the latter.

The Draft Plan Option is almost completely within the North West Orkney proposed MPA, designated for sand eels and marine geomorphology of the Scottish shelf seabed. Furthermore there is overlap with the Papa Westray proposed MPA, designated for Black guillemot and the marine geomorphology of the Scottish shelf seabed.

The seabird maps presented in the baseline indicates the potential for seabird collision and displacement vulnerability during the breeding season, particularly along the south eastern perimeter of the Draft Plan Option as it skirts the islands. However, this vulnerability may differ for individual species.

Cetacean distribution is likely higher in the western portion of the Draft Plan Option. While no Basking shark sightings have been recorded in WN2, several have been recorded in the Orkney Islands, indicating the potential for encounters within the Draft Plan Option. Other elasmobranch species are known to use this area. The importance of the area for both Grey and Common seals is demonstrated by the presence of Seal haul out areas located amongst the islands.

The area is known to be used by fish species, including diadromous species, such as Atlantic salmon, and others including Sea trout and many commercially caught species. The northern region also contains important nursery grounds for several commercially important species of fish.

The seabed in the vicinity of the Draft Plan Option consists mainly of coarse sediments such as sandy gravels and gravelly sands. These benthic habitats are likely to contain species used to strong wave and tidal movements.

Potential vulnerabilities for collision and displacement of diving birds was identified in relation to the Draft Plan Option, particularly in breeding season and along the south eastern perimeter of the Draft Plan Option. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables.

Given the likely presence of marine mammals and fish, particularly Cetaceans and Seals in Scotland's northern waters, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). While avoidance may be possible for some species in some circumstances, there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

The review of current wave technologies identified potential effects from EMF on fish and elasmobranchs although research into the magnitude of effects demonstrates that this is uncertain.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area.

A number of SACs have been identified in the vicinity of the Draft Plan Option with valued and vulnerable coastal and reef habitats. While sediment movement from the installation of wave devices could potentially occur, this will likely depend on the type of device and on the installation technologies used.

The potential remains for collision and displacement of diving birds with the presence of wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain. The western edge of the plan area in particular may coincide with areas used by Basking sharks and Cetaceans.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there would be no significant impacts on diving birds and mobile marine species in the vicinity as a result of collision with wave devices. The results of monitoring from projects currently in the application process and demonstrator sites in Orkney have the potential to help provide greater certainty on the scale of these effects.

It is recommended that the boundary of the Draft Plan Option is kept under review as part ascertaining whether the overlap with the North West Orkney proposed MPA and the Papa Westray proposed MP will remain and would lead to adverse effects, or whether co-location is possible. Projects will need to demonstrate through the EIA process that they are compatible with the conservation objectives of the MPAs.

Further research into the potential collision, displacement and the effects on Cetaceans, Seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

There is likely a risk to Seals in this area, particularly cumulatively, and any offshore development should demonstrate the avoidance of effects on this and other marine fauna species. Similarly, potential impacts on important coastal and reef habitats should also be monitored.

The potential for effects from grid infrastructure could be avoided if supporting onshore/offshore connections were located away from sensitive coastal areas,

It is further recommended that the boundary of the Draft Plan Option is reviewed as part of ascertaining whether the overlap with the Hoy SPA, Marwick SPA and Stromness Heathe and Coast SAC, would lead to adverse effects or whether co-location is possible. Project level HRA must demonstrate development does not adversely affect the integrity of the designations.

Population and Human Health

The waters and coastal areas to the east and north of Orkney are used for a number of industry and recreational activities including fishing, recreational sea angling, recreational cruising, sailing, diving and surfing.

Recreational sailing is popular within this area, for example in and out of Stromness and established routes do cross this Draft Plan Option.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan area were classified as being of good status under the WFD in 2011.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur.

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

Long-term coastal retreat and cliff erosion is occurring around the Orkney coast, particularly along the western coastlines, likely due to the high energy waves present. Several sections along the west coastline have been identified as being vulnerable to coastal erosion ( e.g. largely sheltered beaches and soft coasts). However, little significant or long-term erosion has been observed on the northern coastlines.

The potential for increases in storm events and rising sea levels have been identified, due to the effects of climate change.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics particularly where developments are located near to potentially vulnerable coastlines.

Given the high levels of wave action in this area and the erosion and long term retreat associated with this, developments may in some instances aid the protection of vulnerable coastlines.

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed in the vicinity of the Draft Plan Option consists mainly of coarse sediments such as sandy gravels and gravelly sands.

The depth of the seabed varies from 30 - 170m within the option area, with deeper areas located further to the north west.

The area has generally strong wave energy, particularly in the northern part of the option area, and low tidal energy.

Some seabed disturbance and loss of habitat is likely with the site preparation and placement of device foundations. The scale of such disturbance is likely dependent on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

As such significant increases in turbidity are unlikely given the largely coarse sediments within the Draft Plan Option.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site. This may result in general impacts such as scour, deposition and abrasion in the area and the potential for related impacts to vulnerable coastlines ( e.g. coastlines of Westray and Papa Westray). However, these systems are likely to be complex, and as such, the potential for impacts will be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes, particularly given the identified coastal erosion within nearby parts of Orkney.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used

Historic Environment

There are a significant number of concentrated historic environment assets,(including numerous wrecks, scheduled monuments such as brochs, cairns, and fortifications) within marine and coastal areas near to the Draft Plan Option. The most notable site is the Heart of Neolithic Orkney World Heritage Site which is located to the south of the area. However, much of the Orkney's coastal waters have been identified for their potential for submerged archaeology.

There is the potential for effects on the setting of the Heart of Neolithic Orkney World Heritage Site, particularly from devices with large above water components.

The likely presence of submerged archaeology means that there is potential for direct effects on any remains. However, development which includes archaeological survey may also have some positive effects by contributing to knowledge/understanding about the marine historic environment.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and last for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of sites and seek to mitigate accordingly. Development in this area must demonstrate no adverse effects on the Heart of Neolithic Orkney World Heritage Site.

Landscape / Seascape

The southern end of the Draft Plan Option is likely to be visible from the Hoy and West Mainland NSA, and from both locally designated landscape areas and the coastal edge of the heart of Neolithic Orkney WHS. The Draft Plan Option may also be visible from the Shetland NSA, but this would likely depend on the scale of development and the height of surface-piercing components of renewables devices.

Large parts of the Hoy coastline have a high wildness level.

The Draft Plan Option, particularly in the south and east, are likely to be visible from designated and wild parts of the Orkney coastline.

There is potential for changes to the character of the seascape and potentially on the setting of these designations, including the NSA and WHS.

Visibility effects may occur during construction and maintenance periods as well as during operation. It is likely that navigational aids ( e.g. and marker buoys, lighting) will also have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the option area.

Wave devices at this location, and in particular their supporting infrastructure, may be visible from the Orkney coast, including from areas designated for their landscape importance and as areas of wildness. The significance of potential visual effects in these areas could be greater than for other parts of the coastline.

However, for many wave technologies, the majority of the device infrastructure will be below the water surface and as such, the significance of effects may be lower than for wind technologies. Impacts will also therefore be more likely during construction and maintenance periods than during the operational phase.

The plan option could likely alter the current seascape and potentially affect its character. However, this will depend on the technology used, and the number of human receptors in this remote area may be few. For example, residual visual effects for some technologies could be minimal once constructed.

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts could be greater for offshore receptors, such as recreational sea users.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects. However visual impacts to onshore receptors could potentially be limited by construction further from the coast, in particular the west and north of the Draft Plan Option.

Impacts to the landscape and seascape character would also need to form part of project level assessments.

Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.

WN3

SEA Topic

Summary of Key Baseline Evidence

Potential for effects

Characteristics

Mitigation available and potential residual effects

Biodiversity, Flora and Fauna

The Draft Plan Option covers a large section of the waters to the south west of the Shetland Isles. There are a number of important designations in the vicinity of the Draft Plan Option, including Sumburgh Head SPA, Foula SPA and Papa Stour SPA, all designated for a number of bird species (including Fulmar, Guillemot, and Kittiwake, Skua, Puffin, terns, Guillemot, and Ringed plover). Papa Stour has also been designated as an SAC for its reefs and sea caves. The Draft Plan Option overlaps with Sumburgh Head SPA.

A number of coastal SSSIs, including St Ninian's Tombolo (designated for coastal geomorphology features) have also been identified near to the Draft Plan Option.

A potential vulnerability for collision for diving birds from wave energy devices was identified during breeding season. However, this vulnerability may differ for individual species.

Cetacean distribution is considered high in the Draft Plan Option, particularly in the eastern part nearest to the Shetland coastline. The potential presence of Basking sharks in the vicinity of WN3 is demonstrated by the number of recorded sightings made around the Shetland coastline. Other elasmobranchs are known to use these waters. The importance of the area for both Seals is demonstrated by the presence of Seal haul out areas located amongst the islands. Seal density mapping indicates that Sumburgh Head in particular is regularly used by Common seals.

The area is known to be used by fish species, including diadromous species, such as Atlantic salmon, and others including Sea trout and many commercially caught species. The northern region also contains important nursery grounds for several commercially important species of fish.

The seabed surrounding Shetland consists of largely of gravelly sands and circallittoral coarse sediments. The benthic habitats in this area are likely to contain species used to strong tidal movements and currents, particularly those near to Sumburgh Head.

Potential vulnerabilities for collision and displacement of diving birds was identified in relation to the Draft Plan Option, particularly in the central and northern parts of the Draft Plan Option during breeding season. The potential for impacts likely depends on a range of factors including the bird species considered ( e.g. diving depth can vary markedly between species), the size and design of wind energy devices ( e.g. some diving birds may rest on surface piercing infrastructure during foraging), and the presence or absence of underwater mooring cables.

Given the likely presence of marine mammals and fish, particularly Cetaceans and Seals in Scotland's northern waters, there may be the potential for effects such as barriers to movement, collision with the devices and associated infrastructure, above and below water noise impacts during construction and operation, and aggregation effects ( e.g. aggregation of predators near surface-piercing structures). While avoidance may be possible for some species in some circumstances, there are currently gaps in research knowledge creating difficulty in establishing the likelihood of impacts.

The review of current wave technologies identified potential effects from EMF on fish and elasmobranchs although research into the magnitude of effects demonstrates that this is uncertain.

There is potential for impacts on benthic habitats as a result of scouring, smothering, deposition and abrasion of seabed in areas with coarse sediments as a result of placing devices and supporting infrastructure ( e.g. mooring cables, piling) within this area.

The potential remains for collision and displacement of diving birds with the presence of wave devices. However, the significance of the impact is uncertain as effects on the population viability of individual species are not known.

Potential effects on Cetaceans, Seals, elasmobranchs and fish include barriers to movement, collision with infrastructure, and possible noise impacts as a result of activities associated with installing devices or their anchors. These effects may range from changes to existing feeding behaviour to mortality, although the precise effect on populations cannot be ascertained at this strategic stage but should be a consideration at the project level ( e.g. in monitoring).

Potential for EMF impacts on fish and elasmobranchs from electricity cables associated with wave energy devices. Indirect effects may include altered migratory pathways with unknown energetic/biological consequences.

Effects associated with construction activities would be largely temporary, but the potential for longer term effects from wave devices with underwater infrastructure remain. The western edge of the plan area in particular may coincide with areas used by Basking sharks and Cetaceans.

There is the potential for direct benthic effects associated with the siting and installation of wave devices, and for indirect effects including sediment movements ( i.e. scouring, smothering, sediment deposition and abrasion) from their presence in the marine environment. However, it is expected sediment deposition impacts at this location will be limited as the existing environment is already dynamic.

There may be the potential for significant effects to designated areas associated with installation of grid infrastructure if it were to be sited in the vicinity of the Draft Plan Option.

Project level assessment ( EIA) that includes specific modelling and/or assessment will be required to demonstrate that there would be no significant impacts on diving birds and mobile marine species in the vicinity as a result of collision with wave devices. Given the identified risk of bird collision, consideration to reducing the northern tip of the Draft Plan Option may reduce potential effects. The results of monitoring from projects currently in the application process have the potential to help provide greater certainty on the scale of these effects.

Further research into the potential collision, displacement and the effects on Cetaceans, Seals elasmobranchs and fish will help to identify the potential for significant effects.

To date research has indicated that there are uncertain effects of EMF and noise on fish and elasmobranchs. The results of monitoring of existing and operational projects in this region have the potential to provide greater certainty on the scale of effects.

The potential for effects from grid infrastructure could be avoided if supporting onshore/offshore connections were located away from sensitive areas.

It is recommended that the south west boundary of the Draft Plan Option is kept under review as part of ascertaining whether the overlap with the Sumburgh Head SPA would lead to adverse effects on its integrity or whether co-location is possible.

Population and Human Health

The waters and coastal areas to the south west of Shetland are used for a number of industry and recreational activities including fishing, recreational sea angling, recreational cruising, sailing and bathing.

Sailing routes are popular within this area, particularly between Lerwick, Orkney or Aberdeen.

There is potential for collisions between recreational vessels and offshore energy infrastructure and supporting vessels, particularly during installation. Wave devices that sit low either above or below the water line, and in certain sea conditions could make them harder to see for small craft.

The presence of wave devices has the potential to displace some existing recreational activities, through limiting access to areas of the sea and potential disruption to perceived amenity value.

Any collision could affect vessels and passengers. There remains a potentially significant collision risk for small vessels and wave devices in certain conditions with large waves. In calmer conditions this risk will reduce.

It is difficult to predict the precise impact of potential changes to amenity on recreational use of the area. Some displacement could be permanent leading to recreational activities being discontinued. However it is likely that most activities could continue within a smaller range or in other nearby locations. Some established routes for recreational craft could be required to be diverted.

Potential mitigation for collisions through the inclusion/mapping of offshore energy developments on navigational charts and the use of navigational aids (such as marker buoys and lighting, etc.) in the vicinity of the infrastructure.

When planning projects, developers could work with the recreation sector to consider best how recreational activities might continue within the option boundary. Early consultation can also help to reduce impacts on important cruising routes.

There may be the requirement for commercial shipping to be excluded from developed areas. This would be determined through further engagement between MS- LOT and the relevant navigation authorities at the project level.

Water and the Marine Environment

The coastal waters in the vicinity of the draft plan area were classified as being of good status under the WFD in 2011.

There are a number of designated shellfish waters within the vicinity of the Draft Plan Option around the isles of Shetland.

Potential for adverse water quality impacts during installation, operation and decommissioning of the developments ( e.g. increased turbidity caused by works on the seabed associated with anchoring of devices, contamination from their installation and maintenance vessels).

Some wave devices can use gravity based anchors that will use sediment as fill, and which may carry a pollution risk depending on where the sediment is sourced.

Impacts associated with any contamination from seabed material disturbed during installation or potentially decommissioning is likely to be of localised and temporary nature, with the significance of effects dependant on the level of contamination. Impacts during operation and maintenance are considered less likely.

The significance and characteristic of impacts associated with contamination from vessels is uncertain and cannot be described beyond the potential for it to occur.

Pollution risks associated with installation, maintenance and decommissioning of devices should be reduced and limited through building mitigation into construction procedures, to avoid discharges of harmful material and substances.

Further assessment work may be required to reduce uncertainty regarding potential impacts on water quality, particularly on including shellfish waters. This includes a recommendation for hydrodynamic and water quality modelling as part of project level assessment

Climatic Factors

Littoral processes in Shetland are dominated by wave action, and several sections of the south west Shetland coastline have been identified as being potentially vulnerable to coastal erosion. In several of these areas, erosion processes have been identified previously ( e.g. soft coasts and sandy beaches with beach drawdown and undercutting the coastal edge). Further, varying degrees of cliff erosion have been observed, although this appears to depend on rock type.

The potential for increases in storm events and rising sea levels have been identified, due to the effects of climate change.

Potential for mixed effects on coastal erosion and accretion caused by changes to hydrodynamics from offshore wave developments, particularly for soft coastlines such as soft cliffs and sandy beaches like those in the south west of the Shetland Islands.

Likely contributions to achieving GHG reductions through replacing energy generation from non-renewable sources to renewable sources.

Significance and character of effects are unknown. Depending on how offshore infrastructure affects hydrodynamics the effects on coastal erosion and accretion could be positive or negative. However any effects that do occur are likely to depend on the specific nature and location of the proposed development.

Effects on the coastline are likely to be indirect.

Project level assessment of hydrodynamic changes, as a result of renewables development, should include any relevant climate related changes to the marine environment when assessing impacts.

Marine Geology and Coastal Processes

The seabed in the vicinity of the Draft Plan Option consists mainly of coarse sediments ( i.e. sandy gravels and gravelly sands).

The depth of the seabed is variable over the option area, generally increasing in a south east direction, and reach over 100m in depth in places.

While the area has generally strong wave and low tidal energy resources, an area of stronger tidal resource is located off Sumburgh Head at the southern point of the Shetland Islands.

Some seabed disturbance and loss of habitat is likely with the site preparation and placement of device foundations. The scale of such disturbance is likely dependent on the type and size of the device.

Sediment disturbance caused during the installation process could also lead to secondary impacts such as increased turbidity during installation in areas with fine sediments and release of existing contaminants present in fine sediments. However, water quality impacts from installation works are considered to be less likely in areas of high wave or tidal energies, and where coarse seabed sediments are predominant.

As such significant increases in turbidity are unlikely given the largely coarse sediments within the Draft Plan Option.

There is the potential for offshore developments within the Draft Plan Option to alter sediment dynamics and tidal flow fluxes in the vicinity of the site. This may result in general impacts such as scour, deposition and abrasion in the area and the potential for related impacts to vulnerable coastlines ( e.g. soft coastlines on the south west of the Shetland Isles). However, these systems are likely to be complex, and as such, the potential for impacts is likely to be site specific and dependent on factors such as the type and size of the devices and their foundations/anchors.

Direct impacts such as disturbance of the seabed during installation are likely to be temporary and localised.

Loss of small areas of seabed associated with the installation of foundations/anchors may occur, although some natural regeneration may occur upon decommissioning of devices and removal of anchors.

Changes in sediment dynamics and direct impacts such as scour, deposition and abrasion of seabed sediments are likely to be limited to the installation and operation phases of developments. However, in some circumstances, the effects of such changes may have long-term effects in coastal areas ( e.g. the deposition of sediments in nearby coastal areas).

When projects are in the design process, consideration should be given to the location and arrangement of devices in order to build in mitigation to avoid potential impacts on marine geology and coastal processes, particularly sections of Shetland's coastline sensitive to erosion.

It is recommended that sediment dynamic modelling is undertaken at project level to demonstrate potential effects in order to consider appropriate mitigation.

Mitigation measures could include the design and use of rock scour protection (if required) around the base of any anchors or foundations used.

Historic Environment

This Draft Plan Option area sits close to the southern part of mainland Shetland, Mousa and Bresay, areas which are particularly rich in scheduled monuments such as prehistoric houses, forts, brochs and settlements. In general terms, the coastline of Shetland is particularly sensitive to the impacts of development with many scheduled brochs, and forts along its coast. The most notable is the A-listed Sumburgh Head Lighthouse at the southern tip of the islands.

Several marine and coastal wrecks are located along the south west coastline of the islands, including a cluster immediately south of the Draft Plan Option.

There is the potential for impacts on the setting of coastal historic environment assets, including Sumburgh Head Lighthouse.

The likely presence of submerged archaeology means that there is potential for direct effects on any remains. However, development which includes archaeological survey may also have some positive effects by contributing to knowledge/understanding about the marine historic environment.

Direct effects on historic assets e.g. loss of assets caused by changes to coastal processes or the siting of offshore developments, would likely be permanent. The significance of the effects would, depend on the significance of the receptor.

Effects on the setting of historic environment features would be indirect, and last for the lifespan of the development.

Direct effects on historic environment features can be avoided through appropriate siting of devices away from vulnerable coastlines and known historic marine features.

Project level assessments should consider the potential for impacts on the setting of sites and seek to mitigate accordingly.

Landscape / Seascape

The Draft Plan Option is likely to be visible from several of the component parts of the Shetland NSA. However, this would likely depend on the amount and height of above water infrastructure in any offshore developments.

Much of the Shetland coastline has a high level of wildness.

The Draft Plan Option is likely to be visible from Shetland NSA, Foula NSA, and to the south Shetland NSA. This will depend on whether the devices are above the water surface or are submerged.

It is likely development to the eastern edge of the Draft Plan Option would be the most visible.

There is potential for changes to the character of the seascape and potentially on the setting of the Shetland NSA and Foula NSA.

Effects may occur during construction and maintenance periods as well as during operation. It is likely that navigational aids ( e.g. marker buoys, lighting) will also have visual effects.

There are a number of potential offshore receptors including recreational boats that sail close to the Draft Plan Option.

Wave devices in this area, and in particular its supporting infrastructure, may be visible from the coast, including from areas designated for their landscape importance and as areas of wildness. This can increase the significance of potential visual effects. The significance of potential visual effects in these areas can be greater than for other parts of the coastline.

However, for many wave technologies, the majority of the device infrastructure will be below the water surface and as such, the significance of effects may be lower than for other technologies ( e.g. wind). Impacts will also therefore be more likely during construction and maintenance periods than during the operational phase.

The plan option could be likely alter the current seascape and potentially affect its character. However, this will depend on the technology used, and the number of human receptors in this remote area may be few. For example, residual visual effects for some technologies could be minimal once constructed.

Lighting of wave devices and marker buoys will likely result in some visual effects during day and night, particularly those with a high above water profile or in near shore waters. The significance of effects will depend on the visibility of devices which needs to be established at the project level.

Visual impacts could be greater for offshore receptors, such as recreational sea users.

Full visual impact assessment will be required at the project level ( EIA) to establish the visual envelope and significance of effects. However visual impacts to onshore receptors could potentially be limited by construction further from the coast, in particular to the west of the Draft Plan Option.

Impacts to the landscape and seascape character would also need to form part of project level assessments.

Development that will affect NSA should avoid adverse effects on the integrity of the area or the qualities for which it has been designated.


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