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Indicators of Sustainable Development for Scotland

Indicator 9. Water Quality

Kilometres of river identified as "poor" or "seriously polluted"

Source: SEPA

The relevance of the indicator

Sustainable development means managing our impact on the environment. River quality is important because rivers are a major source of water used for drinking and by industry and leisure. Rivers also support a wide variety of wildlife.

Choice of indicator

It is important that all poor quality or seriously polluted waters are improved. Overall, water quality in Scotland is good; this indicator therefore only reports on the categories of river water quality where action is needed to rectify problems.

Detailed definition and source details

The data used for classification are those obtained from planned programmes of monitoring, including any such samples affected by pollution incidents. River quality is classified in km as excellent (A1), good (A2), fair (B), poor (C) and seriously polluted (D). Data are based on the Scottish Environment Protection Agency's (SEPA's) new Digitised River Network ²¹ which comprises those watercourses draining a catchment of 10 km ² or more, supplemented by those watercourses draining smaller catchments which SEPA are monitoring because their quality has recently been classed as fair, poor or seriously polluted.

River water quality is assessed in 4 measurements: biological, chemical, nutrients (toxicity) and aesthetic. The classification scheme is 'default based', i.e. the overall class of a watercourse at a particular sampling point defaults to the poorest class determined from these 4 quality measurements.

Trends

Although there are variations from year to year in water quality, the overall trend is of improvement. SEPA has set improvement targets; for the period from 1999 to 2001 there has been a reduction of 157 km of class C and D rivers. Quality assessments are made on a year's data, except for chemical classification, for which the data is extended back over 3 years to avoid undue bias resulting from (wet/dry) weather fluctuations. Poor biological quality and nutrient status are the most frequent reason for waters to be classified as poor or seriously polluted. There are a wide range of reasons for this, but primarily it is due to industrial and sewage pollution, as well as problems of agricultural pollution from run off of organic waste and inorganic fertilisers.

Further disaggregation

Further disaggregation of these figures is not currently possible

Target

SEPA are taking action to improve the worst affected rivers first; the overall target for 1999 to 2006 is to reduce the lengths of C (poor) and D (seriously polluted) class rivers by 351 kilometres. ²²

Action

We plan to extend the monitoring information to protect good and excellent quality waters as part of the river basin management plans in the Water Environment and Water Services (Scotland) Bill.

The Executive has worked with stakeholders to introduce measures to mitigate and reduce water pollution problems resulting from urban and agricultural diffuse pollution, with specific action in nitrate vulnerable zones (NVZs) and for bathing waters. In particular, the Sustainable Urban Drainage Manual and the 4 Point Plan, which was launched on 18 November, provide advice to help protect the water environment.

In terms of actions to mitigate sewage pollution, the Quality and Standards process sets out the environmental and drinking water standards the water authority must meet and estimates the investment that is required. We are investing in secondary sewage treatment for more than 80% of Scotland's population. Additionally, under the Water Industry (Scotland) Act 2002, the aim is to have a sustainable development policy prepared early in 2003.

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