The case of Ian Cook v South West Water PLC was heard at Exeter County Court in April. The plaintiff argued that discharges from three of the company's sewage works had interfered with his common law rights of riparian ownership. The damage was alleged to have been caused by a combination of elevated levels of phosphate in the river, resulting in an increase in algal growth, and by foaming caused by detergents in the sewage effluent. Mr Cook produced photographic evidence of algal growth and the testimony of an expert witness that a stretch of the river had deteriorated in quality due to the growth of brown algae.
But Judge Anthony Cox accepted the evidence of an expert witness for the defence on the phosphate issue. Dr Alabaster, a former Water Research Centre scientist, told the court that phosphate levels between 0.1-0.7mg/l would not increase algal growth. The level of phosphate in the river at the time of the alleged damage was below 0.7mg/l.
The stretch of river in question had been designated as a salmonid fishery under the EC Directive on freshwater fish. The judge was persuaded by Dr Alabaster's evidence that an observation in the Directive that a phosphate level of 0.2mg/l for salmonid waters may be regarded as indicative of eutrophication had no scientific basis.
On the second question, however, the court accepted Mr Cook's claim that there was a persistent coverage of foam on the river during the 1990 fishing season, and that this was due to detergents in the sewage effluents.
In an aspect of his ruling which may have wider implications, the judge agreed with the plaintiff's contention that South West Water's discharge consents permitted the discharge of only those substances specifically identified in them, and any others which would have no appreciable effect on the receiving waters.
The concept of "appreciable effect" was introduced by section 36 of the Control of Pollution Act 1974, which provided for the advertisement of applications for discharge consents but allowed the authorities to disregard this requirement in the case of discharges which they considered would have no "appreciable effect" on the receiving waters. Guidance was subsequently issued by the Department of the Environment on how this phrase should be interpreted.
Drawing on this, the judge ruled that the detergents present in the sewage discharges had caused an "appreciable effect" on an amenity area of environmental significance, and were changing the water quality in such a way as to damage existing and future uses of the waters. Finding in Mr Cook's favour on this count, he ordered South West Water to pay damages of £2,500. The company was also told to pay costs of £1,500.