e-Digest Statistics about: Coastal and marine waters
Estuaries
Quality
Information about the quality of estuaries in the UK is given in Table 6. In England, Wales and Northern Ireland, and in Scotland up until 1995 estuaries are categorised into four quality classes, "good", "fair", "poor" and "bad", based on the biological, aesthetic and chemical quality of the water. A points system is used to classify waters, where points are awarded if certain criteria are met and the total points count for the estuary determines its quality class. In Scotland a new classification system was introduced in 1995, called the Association of Directors and River Inspectors for Scotland (ADRIS) estuary scheme. As with the previous scheme, ADRIS is based on the biological, aesthetic and chemical quality of water, but the criteria are more comprehensive and more precisely defined. In order to achieve a particular classification under the ADRIS scheme waters must satisfy all the quality criteria appropriate to the class. In this scheme, estuaries are also divided into four quality classes; categorised as "excellent", "good", "fair/poor" and "seriously polluted". Northern Ireland is changing over to the ADRIS scheme and will present results in future years based on this new classification. The Environment Agency is also considering changing the classification system in England and Wales to a more objective and comprehensive General Quality Assessment.
Between 1980 and 1995 estuary quality remained fairly consistent. The latest information for 2000 shows an improvement in England and Wales, with an increase in the proportion of estuaries classified as good or fair. In Northern Ireland, quality remained the same in each of the classes between 1985 and 1993, after taking into account the inclusion of sea loughs from 1991. Eighty-eight per cent of estuary length was classed as good in 1993 (no estuary lengths fell into the "fair" category). In Scotland, estuary quality improved between 1990 and 1995, and has remained fairly consistent since then. 95 per cent of Scottish estuaries are currently classified as excellent or good.
Further Information:
- Data Tables:
- 6 Quality of estuaries : 1980-2005 XLS
- Internet Links:
- e-digest: Concentrations of dissolved metals
- Environment Agency
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Page last modified: 16 September 2003
Page published: 10 September 2003