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Water - River Water Quality

High Level Summary of Statistics Trend Last update: Tuesday, October 3, 2017

River Water Quality

Low standards of river water quality may threaten the aquatic environment, drinking water quality and recreational water use. Sewage, industry, urban development and agriculture are some of the factors that may affect river water quality.

The Scottish Environment Protection Agency (SEPA) has established an indicator of river water quality based on a network of sites covering 253 water bodies (rivers, or sections of rivers), which account for approximately 10% of all water bodies. The indicator is based on a consistent set of five water quality parameters which are sensitive to organic pollution, nutrients and toxic substances and provide a measure of species diversity. Each of the parameters is assessed over a rolling 3 year period and the results weighted by river length.

The assessment is against the standards provided for each parameter in the Water Framework Directive classification. Two of the Water Framework Directive standards, invertebrates and phosphorus, used to calculate the indicator were changed in 2013; SEPA is looking into back calculating the indicator values potentially as far back as 2007 using the new standards to provide a consistent time series

The proportion of river length that was classed as slightly polluted, polluted or severely polluted in Scotland rose from 6.8% in 1992, to 7.4% in 1998, before falling to 3.4% in 2013, using the old standards. Using the new standards, this proportion fell from 3.7% in 2013 to 3.1% in 2016. The proportion of river length classed as unpolluted fell from 86.5% in 2010 to 84.8% in 2013. Using the new standards, the proportion of river length classed as unpolluted rose from 83.3% in 2013 to 85.1% in 2016. In 2016, the proportion of river length classed as unimpacted by pollution was 11.9%.

River Water Quality 1992 to 2016

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Source: Scottish Environment Protection Agency

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