Assessing the effectiveness of regulatory controls on farm pollution using chemical and biological indices of water quality and pollution statistics

• Published in: Water research (Oxford) 2001-08, Vol.35 (12), p.3004-3012
• Main Authors: Foy, R.H, Lennox, S.D, Smith, R.V
• Format: Article
• Language: English
• Subjects: Agriculture; Agrochemicals; Animals; Applied sciences; Biological effects; British Isles, Northern Ireland; Catchments; Continental surface waters; Cyprinidae - growth & development; Earth sciences; Earth, ocean, space; Ecosystem; Effluents; Engineering and environment geology. Geothermics; Environmental Monitoring - standards; Environmental Monitoring - statistics & numerical data; Exact sciences and technology; Farms; Fresh Water - chemistry; Invertebrates - growth & development; Ireland; monitoring; Natural water pollution; Oxygen - metabolism; Oxygen Consumption; Pollution; Pollution control; Pollution, environment geology; Quaternary Ammonium Compounds - metabolism; Runoff; Salmonidae; Salmonidae - growth & development; trends; water; Water Movements; Water Pollutants, Chemical - analysis; Water Pollution - analysis; Water Pollution - prevention & control; Water Pollution, Chemical - analysis; Water Pollution, Chemical - prevention & control; Water quality; Water Supply - analysis; Water Supply - standards; Water Supply - statistics & numerical data; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/S0043-1354(00)00587-X

Water quality was measured in 42 streams in the Colebrooke and Upper Bann catchments in Northern Ireland over the period 1990–1998. Despite ongoing pollution control measures, biological water quality, as determined by the invertebrate average score per taxon (ASPT) index, did not improve and there was no appreciable decline in recorded farm pollution incidents. However, the lack of decline in pollution incidents could reflect changes in detection policy, as a greater proportion of incidents were recorded from less polluting discharges such as farm-yard runoff. In contrast, there was an improvement during 1997 and 1998 in annual chemical water quality classification based on exceedence values (90th percentiles) for dissolved oxygen, ammonium and BOD concentrations. In 1998, 11.9% of streams were severely polluted compared to 26.2% in 1990, while the proportion classed as of salmonid water quality, increased from 40.5% in 1990 to 59.6% in 1998. Although water quality in 1996 did not improve relative to 1990 values, there was a notable increasing trend from 1990 in the numbers of samples taken during the summer which had good water quality with low ammonium (70% sat). The trend for samples with low BOD (