Eutrophication of Tamar Lakes (1975-2003): a case study of land-use impacts, potential solutions and fundamental issues for the Water Framework Directive

• Published in: Water and environment journal : WEJ Vol. 20; no. 3; pp. 159 - 168
• Main Authors: Hendry, Keith, Sambrook, Hugh, Underwood, Chris, Waterfall, Rachel, Williams, Adrian
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.09.2006; LeadMedia
• Subjects: agricultural runoff; agriculture; algal blooms; ammonia; Applied sciences; biochemical oxygen demand; Biological and physicochemical phenomena; CAP; case studies; catchment management; Common Agricultural Policy; Continental surface waters; Cyanobacteria; diffuse pollution; drainage; Drinking water and swimming-pool water. Desalination; England; environmental impact; eutrophication; Exact sciences and technology; lakes; land use; livestock; livestock production; monitoring; Natural water pollution; nonpoint source pollution; nutrients; pollutants; Pollution; rain; resource management; rivers; slurries; water pollution; water quality; water reservoirs; water treatment; Water treatment and pollution; WFD; England; Drinking water; Water treatment; Water supply; Eutrophication; nutrients; Rain; WFD; Watershed; Agriculture; Stream; diffuse pollution; catchment management; monitoring; Coastal lagoon; Ammonia; Pollutant; CAP; Surveillance; Fuel; Surface water; Water quality; Lakes; Livestock; Physicochemical purification; Water pollution; Resource management; Farming
• ISSN: 1747-6585; 1747-6593
• DOI: 10.1111/j.1747-6593.2006.00034.x

Tamar Lakes is comprised of two reservoirs, which are located in South West England and in the headwaters of River Tamar at approximately 135 m above ordnance datum. Upper Tamar Lake (UTL) is a direct feed source reservoir of potable water in North Cornwall. Immediately following completion in 1975, UTL was subject to intense blue‐green algal blooms that continue to the present. These blooms create operational problems for water treatment, especially in hot‐dry years. Lower Tamar Lake (LTL) was constructed as a water supply reservoir in 1819 and became obsolete following UTL coming on‐line. Detailed water quality investigations over a period of some 28 years have confirmed the source of nutrient enrichment that fuels the algal blooms to be agriculturally derived, corresponding with a substantial increase in livestock farming. Associated poor land management practices, such as extensive field drainage and inappropriate slurry disposal to land, are linked with substantial elevations in organic contaminants such as ammonia, biochemical oxygen demand (BOD) and suspended solids (SS) during rainfall events. Evidence demonstrates that both reservoirs act as primary treatment lagoons, substantially reducing the worst of these pollutants and providing significant environmental gain. The implications of the Common Agricultural Policy (CAP), the Water Framework Directive (WFD) and regulatory monitoring are discussed in relation to resource management.