Nitrate Vulnerable Zones Action Programme review: consultation

3. Background

3.1 The Nitrates Directive

In 1991, the European Union adopted the Nitrates Directive 91/676/EEC on Pollution Caused by Nitrates from Agricultural Sources. It is intended to control and reduce the loss of nitrate from farming and thus to protect the water environment. It requires Member States to identify and designate areas where nitrate concentrations in water have reached or are approaching 50 milligrams per litre (mg/l). These areas are Nitrate Vulnerable Zones (NVZs), where measures have to be in place to control the storage and application to land of nitrogen (N) compounds, especially manufactured fertilisers and livestock manures.

There are two main reasons why nitrate concentrations in the water environment should be kept below prescribed limits:

• high nitrate concentrations can contaminate drinking water sources. The Public Water Supplies (Scotland) Regulations 2014 require water supplied as drinking water to have a nitrate concentration less than 50 mg NO₃/l.

• high nitrate concentrations can contribute to an overall deterioration in water quality and lead to eutrophication, where nutrient enrichment results in undesirable disturbances of aquatic ecosystems in both fresh and sea water. Amongst other things, toxic algal blooms can develop and the oxygen status of water is reduced, leading to fish kills and a reduction in the biodiversity and conservation value of affected water bodies.

The run-off or leaching of nutrients, such as nitrate, from agricultural activities is a significant cause of poor quality in some of Scotland's rivers, lochs and groundwater. Groundwater nitrate concentrations have risen in the past few decades, and in some places within all NVZs they exceed the threshold level of 50 milligrams of nitrate in a litre of water (50 mg/l).

3.2 The Scottish Nitrate Vulnerable Zones

Five NVZs are currently designated in Scotland, and cover 10% of the Scottish land area:

• Aberdeenshire, Moray, Banff and Buchan;
• Strathmore and Fife;
• Lothians and Borders;
• Lower Nithsdale: and
• Stranraer Lowlands.

The Scottish Government reviewed the NVZ designations in Scotland in 2024, and no changes were proposed at that time.

3.3 Nitrate monitoring summary

The Scottish Government published a report^[1] on 31 December 2024, which gave a summary of the monitoring undertaken by the Scottish Environment Protection Agency (SEPA) and the annual nitrates values for surface waters and groundwaters. The water quality section of the report showed that surface waters are less impacted by nitrate from agricultural sources than groundwater. The surface water data provides an insight into the water quality of the catchment, and the groundwater data implies more localised water quality.

Monitoring has shown that surface water sites have continued to maintain a high standard of water quality. This is expected to continue, although with surface waters in Scotland already in good condition with respect to nitrates any improvement will continue to be small.

Although there has been no strong trend in the concentration of nitrates in groundwater, the number of sites averaging over 37.5 mgNO₃/l has continued to decrease since 2016. This suggests that measures in place to reduce nitrates are having a positive impact. However, SEPA’s monitoring of groundwater indicates that 14.21% of stations within Nitrate Vulnerable Zones (NVZ) have annual average concentrations in excess of the 50 mg NO₃/L (the nitrate drinking water limit). This shows that those areas of groundwater bodies that are at the highest risk continue to be predominantly within the NVZs, and suggests that measures set out in the Action Programme focus on the right areas.

Any improvements in groundwater quality from the aims of Action Programme measures are likely to be very slow. A review^[2] of the scientific literature funded by the Scottish Government indicates that positive responses to mitigation measures for nitrogen in groundwater have no fixed timeframes for improvement, and lags in response are likely to be longer than 20 years.

3.4 The current NVZ Action Programme

The Action Programme for Nitrate Vulnerable Zones (Scotland) Regulations 2008 introduced the revised Action Programme with effect from 1 January 2009. The Action Programme for Nitrate Vulnerable Zones (Scotland) Amendment Regulations 2013 came into force on 15 May 2013 and introduced further controls. The Action Programme sets out the measures that farmers must comply with on land lying within the NVZs.

The Action Programme includes:

• Limits on the quantity of nitrogen applied to crops and grassland
• Restrictions on the timing of nitrogen applications (closed periods)
• Annual farm limit of nitrogen in livestock manure
• Storage requirements for slurry, silage, poultry manure and farmyard manure
• Other restrictions on nitrogen application, and
• Record-keeping requirements (including preparation of a Fertiliser and Manure Plan).

The Scottish Government has a webpage with further information on Nitrate Vulnerable Zones and the requirements of the Action Programme. The Scottish Government’s 'Guidelines for farmers in nitrate vulnerable zones' provide general and technical information to help farmers to comply with Action Programme measures.

Since 2013, the Scottish Government has introduced a range of measures across Scotland to reduce diffuse pollution (eg nitrates, phosphorus, sedimentation and faecal indicator organisms) from agricultural activities, including within NVZs through the Water Environment (Controlled Activities) (Scotland) Regulations 2011 (CAR). The most recent amendments introduced through the Water Environment (Controlled Activities) (Scotland) Amendment Regulations 2021 are currently being phased in through a transition period up to 2027. This has continued the innovative introduction of statutory General Binding Rules (GBRs), which aim to reduce diffuse pollution, including nitrogen, from agricultural activities.

Most recently, The Water Environment (Controlled Activities) (Scotland) Amendment Regulations 2021 updated and consolidated into CAR the Control of Pollution (Silage, Slurry and Agricultural Fuel Oil) (Scotland) Regulations 2003 (SSAFO), which are now revoked.

In addition to the consolidation of SSAFO, the 2021 Amendment Regulations also included provisions, with the following key aims:

• to update existing controls for the storage of slurry and silage
• to introduce controls over the storage of materials associated with energy production from anaerobic digestion; and
• to introduce new requirements regarding more targeted and efficient application of slurry and liquid digestate.

These continuously updated CAR GBR diffuse pollution measures add additional requirements for farmers to follow within NVZs where the NVZ Action Programme does not already set more stringent measures. The Water Environment (Controlled Activities) (Scotland) Regulations 2011 diffuse pollution mitigation measures will continue when they are replaced by the Environmental Authorisation (Scotland) Regulations 2018 from 1 November 2025.