Water quality has improved significantly over the last two decades.
By working with the water industry and other interested organisations, we've dealt with many of the major sources of pollution that are affecting our waterways.
We're now changing the way we measure the quality of the water environment to help us focus on other sources of pollution so we can continue to protect and enhance the health of the public, animals, plants and habitats.
How did we used to measure water quality?
For the last twenty years, we've used a general quality assessment (GQA) scheme to assess river water quality in terms of chemistry, biology and nutrients. GQA has helped drive environmental improvements by dealing with the main sources of pollutants, such as discharges from sewage treatment works.
We now need a more sophisticated way of assessing the whole water environment that will help us direct action to where it's most needed. The European Water Framework Directive (WFD) will allow us to do this.
River water quality
River water quality has generally improved over the past couple of decades in terms of chemistry and biology (Indicator: rivers of good or excellent quality). We’ve also seen a fall in the amount of nutrients in our rivers over this time (Indicator: rivers with high levels of nutrients).
Biological quality - an indicator of overall health of rivers
Our aim is to get as many rivers as possible iclassed as excellent or good. In 2008, 72 per cent of English rivers were at this level - the best on record, this is up from 55 per cent in 1990.
88 per cent of Welsh rivers were of good or excellent quality - again, the best on record, compared with 79 per cent in 1990.
Chemical quality - an indicator of organic pollution in general
In 2008 79 per cent of English rivers were at excellent or good quality, up from 55 per cent in 1990.
95 per cent of Welsh rivers were of good or better quality, up from 86 per cent in 1990.
Nutrient status - phosphate and nitrate in rivers
Our aim is to continue to reduce the number of rivers with high concentrations of nutrients. High concentrations are classed as greater than 0.1mg/l for phosphate and 30mg/l for nitrate.
In 2008, 51 per cent of English rivers had high concentrations of phosphate compared with 69 per cent in 1990. High concentrations of nitrate were found in 32 per cent of English rivers in 2008 compared with 36 per cent in 1995.
8.5 per cent of Welsh rivers had high concentrations of phosphate in 2008, compared 26 per cent in 1990. High concentrations of nitrate rarely occur in Welsh rivers.
How does this compare with classification results for the WFD?
Under the EU Water Framework Directive (WFD), water quality assessments are being published using a new, tougher methodology. WFD monitoring, known as classification, is risk-based and focuses where there is likely to be a problem. It uses a principle of ‘one out, all out’ which means that the poorest individual result drives the overall.
It also is based on a far wider range of assessments than GQA classification. It reports on over 30 measures, grouped into ecological status (including biology and ‘elements’ such as phosphorus and pH) and chemical status (‘priority substances’). The WFD also covers estuaries, coastal waters, groundwater and lakes as well as rivers.
Differences in the data
The changes to the assessments means that WFD results appear significantly different to GQA data. We need to be careful when comparing the two. To make this easier, we are running the WFD and GQA classifications at the same time for 3 years. In 2011 we will follow the WFD classification only.
The important point is that we are using a more sophisticated way of measuring the water environment that looks at the impact of all pressures and allows us to deal with the biggest issues.
Using the new classification system, results for assessed rivers in England and Wales show that for overall ecological classification 26 per cent of rivers are good or better, 60 per cent are moderate, 12 per cent are poor and 2 per cent are bad.
Results for all assessed surface water bodies show that 29 per cent meet good ecological status or better, which includes 36 per cent of lakes and 27 per cent of estuaries and coastal waters (Figure 1: status of all water bodies).
Results for assessed groundwaters show that 65 per cent meet good quantitative status (in relation to groundwater abstraction pressures) and 59 per cent meet good status for chemicals.
These figures include the ecological potential where water bodies are artificial or heavily modified. Some water bodies will never achieve good ecological status because they have been physically altered for a specific use, such as navigation, recreation, water storage or flood protection. Ecological potential is based on the quality that can be achieved given a waterbody’s changed conditions.
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