WATERSHED MANAGEMENT USING WATER QUALITY MODELING TOOLS

This paper identifies selected planning level tools for developing cost-effective methods of protecting and enhancing receiving water quality using a watershed approach and adaptive management. The watershed approach includes evaluation of pollutant loads and receiving water impacts and evaluation of pollutant removals and costs. The planning tools include unit pollutant transfer coefficients, continuous simulation, and economic optimization.The use of unit transfer coefficients provides a rationale for estimating the in-stream water quality concentrations associated with various alternative combinations of point source pollutant loadings for specified hydraulic conditions. Continuous simulation techniques quantify the response of both point and intermittent nonpoint sources of loading on a receiving water body. Economic optimization procedures provide a defensible basis for selecting a least-cost mix of technologies to achieve specified water quality protection goals. The use of each tool is discussed with respect to guiding decision-making using adaptive management.