Advance in river quality continues

New data produced by the National Rivers Authority (NRA) have confirmed that river quality in England and Wales has been on an improving trend since 1990. But there is no evidence that it has regained the historically high standards reached around 1980.

Earlier this year the NRA announced a new system of classifying the chemical quality of rivers called the General Quality Assessment (GQA). This has now superseded the old classification established by the National Water Council (ENDS Report 232, pp 4-5 ).

To establish the new system, the NRA classified river quality in 1990 using both systems, making 1990 the baseline for future comparison. A GQA is based on averages of three years' data, so the results just released for 1991-93 (see table ) are the first full set after the 1990 baseline. Also included in the table is an interim GQA based on only 1991 and 1992 data which the NRA published in May.

The figures show a clear improvement since 1990. The NRA says that this is equivalent to an overall net upgrading of over 15% of the length of rivers and canals surveyed. Improvements were particularly apparent in the North West, South Western and Welsh regions.

However, significant reductions in the length of the best Class A rivers were recorded in the Severn Trent, Southern and Thames regions. In Severn Trent there was also an increase in badly pollution Class F rivers.

The overall improvement is not as impressive as it seems because 1990, and the preceding two years, represented the lowest point in river quality since the 1970s. The drought during this period also exacerbated the effects of pollution.

However, because of the changeover to the GQA classification, comparison with water quality prior to 1990 is no longer straightforward.

A comparison of 1992 data with river quality objectives set in the early 1980s was conducted by ENDS earlier this year (ENDS Report 232, pp 4-5 ). This showed that, where data were available, river quality was often below 1980 levels. Although the latest figures represent a 4.3% improvement on the 1992 data, there is no good evidence that the decline in river quality since 1980 has yet been made good.

A new NRA report on compliance with the 1978 EC Directive on freshwater fisheries also suggests that river quality is still at or below early 1980s levels.1 The Directive requires waters designated as either cyprinid or salmonid fisheries to meet quality criteria designed to ensure sustainable fish populations. Some 20,000 kilometres of freshwaters in England and Wales, plus about 1,000 hectares of lakes, were designated by the Government in 1980.

The report concludes that the percentage of river lengths complying with the Directive increased from 93% in 1989 to 95% in 1992 (see table ). However, in 1985 compliance stood at 94% and there are good reasons to believe that this was a conservative assessment.

Article 11 of the Directive allows "derogations" from the standards in respect of the weather, geography or enrichment from the soil, and Annex 1 also allows derogations for ammonia levels provided there are no adverse effects of fish. Increasing use has been made of these derogations since 1984. In that year, 57 Article 11 derogations were applied, but none under Annex 1. In 1989, the derogations increased to 89 under Article 11 and 73 under Annex 1. And in 1992, 119 were made under Article 11 and 26 under Annex 1.

Waters designated under the Directive represent a major part of the better quality freshwaters in England and Wales. Although the data confirm an improvement in quality between 1990 and 1992, the present standards appear to be, at best, no better than in 1984.

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