SPREADSHEET-BASED TOOL FOR ESTIMATING POLLUTANT LOAD REDUCTIONS DUE TO BEST MANAGEMENT PRACTICE IMPLEMENTATION AT THE WATERSHED LEVEL

A comprehensive spreadsheet tool for estimating pollutant loads and load reductions at the watershed level for nutrients (nitrogen and phosphorus), sediments, and organic compounds (e.g. Biological Oxygen Demand) was developed. The spreadsheet tool can be created dynamically based on user specifications (number of watersheds, animal types, and land uses) using easy-to-follow graphical user's interfaces (GUI). The input for the tool includes land use areas, population on septic systems, agricultural animals, manure applications, Best Management Practice (BMP) efficiencies and soil erosion parameter values. Pollutant load and/or erosion potential are calculated for cropland, pastureland, forest, and urban areas. Sediment delivery ratios are calculated at two levels, i.e., source area less than 200 acres and source area greater than 200 acres. Nutrient and sediment reduction are evaluated and estimated by selecting various BMP options (types and efficiencies). The pollutant load and reduction results are presented in summary tables and graphs that are linked dynamically to the data sources. This tool is expected to assist federal, state, and local organizations in implementing their point and nonpoint source programs, Farm Bill programs, TMDLs, and other water quality-related programs.