Assessment of water quality by total maximum daily load (TMDL)analysis

This study comprised of development of the new strategy to give better insight for the management of surface waters. This strategy is based on ?Total Maximum Daily Load (TMDL)? analysis and aims sustainable basin management. Beneficial use designation is suggested being used as first step of the establishing strategy. The next step comprises interrogation of water quality to state whether or in which degree quality of water supports intended use. Water quality is defined by numerous variables (parameters). Selection of variables having significance for intended uses, determination of numerical limits for these variables are required and standards are suggested being used as a reference in this context. Existence of long list of variables defining overall water quality makes the procedure difficult and complicated. Application of environmetric analysis and water quality index methods is proposed to assist water experts in assessment process. Determination of indicator (key) variable(s) that are under pollution risk is another crucial component of the process. Indicator variable(s) will be the core for basin growth assumptions. Water quality modeling step intends to establish the causeand- effect relationship between the key variable in waterbody and the pollutant sources. In this scope, pollutant loads from each source and total maximum daily load assimilated by the waterbody without exceeding standards are determined. In addition, alternative scenarios are developed to see effects of basin growth for various land uses on water quality. Each scenario ensures that water quality will attain and maintain water quality standards. Load contributions from pollution sources are investigated for each scenario to determine balance between pollutants originating from point and non-point sources. In the final stage, decision on basin growth and management plan is taken by policy makers.The proposed approach was validated through a systematic application study in a field case in Turkey. Results revealed that decision process could assist policy makers developing realistic strategies taking into account the basin specific conditions. Keywords: Environmetric methods, Tahtali Basin, Total Maximum Daily Load (TMDL) analysis, water quality index, water quality management strategy.