River Catchment Management: An Approach to the Derivation of Quality Standards for Farm Pollution and Storm Sewage Discharges

Water quality in certain UK rivers has deteriorated due to episodic pollution from farms and storm sewage overflows. In response to the need to further our knowledge of the effects of episodic events on water quality and to derive appropriate quality standards, WRc Environment has established a number of case studies involving both field and laboratory investigations. This paper describes the approach to standard setting which has been adopted in these studies. Two complementary approaches are used: the first based on examining published toxicity data in order to derive working draft standards; the second is the testing of these draft standards against the performance of living organisms.