« Previous | Contents | Next »
Listen
Indicator 9. Water Quality
Kilometres of river identified as "poor" or "seriously polluted"
Year | 1999 | 2000 | 2001 | 2002 | 2003 | 2004 |
|---|
Poor | 1,078km | 854km | 929km | 903km | 751km | 717 km |
|---|
Seriously polluted | 91km | 73km | 83km | 56km | 53km | 51km |
|---|
Total of poor or seriously polluted | 1,169km | 927km | 1,012km | 959km | 803km | 757km |
|---|
Length of digitised river network* | 25,382km | 25,455km | 25,511km | 25,445km | 25,436km | 25,434km |
|---|
Source: SEPA
* The length of the digitised river network fluctuates each year as it only includes those rivers that are monitored and SEPA does not monitor small headwater streams if the water quality downstream has been upgraded to good or excellent.
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 and biodiversity.
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) Digitised River Network 1, 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 2004 there has been a reduction of 402km 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 is 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 2.
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) Act 2003.
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, 4 Point Plan (for farmers), and Guidelines for Farmers in Nitrate Vulnerable Zones provide advice to help protect the water environment. The Executive has also published a series of Codes of Practice to ensure certain activities do not pollute groundwater, which is important to surface water flows 3.
In terms of actions to mitigate sewage pollution, the Quality and Standards 2 investment programme sets out the environmental standards Scottish Water must meet in the period to 2006.
In accordance with the Water Industry (Scotland) Act 2002, a sustainable development policy for Scottish water is currently being developed. Scottish Water published a sustainability report for 2002-03 in June 2003 4.
Footnotes1 More information can be found on the SEPA website at: www.sepa.org.uk
2 The target published in Meeting the Needs… was to improve 315km by 2006-07.
3 These documents are available on the Scottish Executive website at: www.scotland.gov.uk/about/ERAD/WEU/00015561/Guidance.aspx
4 Available on the Scottish Water website at: www.scottishwater.co.uk
« Previous | Contents | Next »