HC Deb 30 April 1986 vol 96 cc405-6W
Mr. Powley

asked the Secretary of State for the Environment when he expects to publish the report of his Department's acid waters review group; and if he will make a statement.

Mr. Waldegrave

The interim report by the United Kingdom Acid Waters Review Group is being published today. I have arranged for copies to be placed in the Library.

The group's report assesses the data currently available and sets out the scientific background to the various processes that may contribute to freshwater acidity. Criteria and definitions for identifying acidific waters are recommended and methods and guidelines for monitoring freshwaters are reviewed.

The report notes that acidification has been identified in some distinct geological regions of the north of England, south-west Scotland and Wales, but that there is no evidence of widespread acidification of United Kingdom freshwaters generally. It discusses the decline of salmon and trout fisheries in some parts of Scotland and Wales, and suggests that the importance of land use practices for fisheries may be indicated by the tendency for poor fishery status to correlate with afforested catchment areas, although a casual relationship between afforestation and fishery decline has not been established.

The report notes that available data on the chemical and biological status of freshwaters were mostly obtained for purposes other than the assessment of freshwater acidification, and are not generally of the quality required to produce the clear picture of historical trends which is needed to establish whether links exist between freshwater acidification and acid rain or other factors such as soil chemistry or land use practices. Of the 75 sets of acidity data examined only six appear to give firm evidence of increasing acidity.

I have decided that we need a better picture of freshwater acidification and am taking steps to extend monitoring work in order to improve our understanding. Work already in progress under my Department's research programme on the analysis of diatom remains in sediment cores will also be extended to surfact waters in other regions identified in the report as susceptible to acidification.

The group's final report, due in late 1987 or early 1988, will draw on the results of current research and monitoring and aim to assess both the probable causes of freshwater acidification and the possibilities for remedial measures.

Mr. Chris Smith

asked the Secretary of State for the Environment what systematic monitoring for acid pollution is carried out in rivers in England.

Mrs. Rumbold

The water authorities routinely monitor the acidity of rivers as part of their general responsibility for water quality monitoring. Specific monitoring of acidity is carried out in certain areas of the United Kingdom which may be susceptible to surface water acidification. In England, continuous measurements of acidity are made on the Rivers Esk and Duddon as part of a joint project between my Department and the North West water authority. My Department is also funding the study being carried out by the river purification boards into the effects of acid deposition on Scottish catchments, and co-funding the study of catchment systems feeding the Llyn Brianne reservoir, which is being carried out jointly with the Welsh water authority, the Natural Environment Research Council and the University College of North Wales, Bangor.

Mr. Chris Smith

asked the Secretary of State for the Environment if salmon and trout found dead on river banks are tested for signs of poisoning related to surface water acidification; and if he will make a statement.

Mrs. Rumbold

No. There is strong circumstantial evidence that short-lived pulses of high acidity associated with snow melt or the on-set of rain following a dry period have caused occasional fish kills in rivers, but fish killed in these circumstances show no distinctive signs and there is no test to distinguish them from those which have died naturally. Fish living in chronically acidified waters—generally lakes—may show observable signs of gill-clogging or skeletal deformity, but these symptons may not be indicative of acidification damage only.

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