Point and nonpoint sources of nutrients to lakes – ecotechnological measures and mitigation methodologies – case study

Abstract

Abstract Although Lake Egirdir is Turkey's second largest freshwater lake and the drinking and irrigation water resource for 350,000 people around the reservoir, it does not have a management plan. This study covers the nutrient influx from point and nonpoint sources, based on data that were obtained from a project that was performed in the reservoir of Lake Egirdir between 2000 and 2007. The impact of the point sources on the lake was determined, and appropriate sustainable treatment systems were designed to minimize the impact, whereby treatment technologies were developed for five select pilot settlement areas for testing purposes. Other studies attempted to assess the impact of pollution from point and nonpoint sources. The collective data suggest that several precautions can be taken to reduce nutrient input into the lake's reservoir. Presently, 1514.4 and 150.5 t/year of total nitrogen and phosphorus, respectively, enter Lake Egirdir from point and nonpoint sources. The successful implementation of projects that have been prepared for point sources may reduce total nitrogen pollution by 79% and total phosphorus by 30–50%. The nutrients that come from nonpoint sources, except from atmospheric deposition, can decrease by a minimum of 50% through effective control techniques.