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The Watershed Management Modeling System (WMMS) is a tool developed for application in LA County watersheds that combines a watershed and receiving water model with a structural BMP performance model to identify cost-effective implementation strategies.

The Windows-based interface allows a user to establish runoff volumes and pollutant loads for baseline and post-BMP conditions and evaluate potential structural stormwater BMP scenarios in their area of interest without having extensive watershed modeling expertise. WMMS is comprised of two components: Loading Simulation Program C++ (LSPC, another model defined in this database), and the Regional Optimization system. With the RegionalOptimization system, WMMS is capable of evaluating cost-effective combinations of local-scale low impact development (LID) type BMPs and watershed scale BMPs. The model determines the optimal distribution that attains the desired Total Maximum Daily Load (TMDL) targets for a variety of pollutants for the lowestBMP implementation cost. WMMS utilizes the System for Urban Stormwater Treatment and AnalysisIntegration (SUTAIN, another model defined in this database) to calculate the most cost-effective set ofBMPs, and optimizes its results for large scale analysis.

Intended User: WMMS is intended for use by stormwater program managers in LA County. To run analyses outside the scope of the current model, expertise in watershed modeling is recommended.

Geographic focus: Model defaults Geographic focus: are specific to LA County.

Scale: Watershed

Developer: Tetra Tech, on behalf of Los Angeles County Flood Control District.

  • How are source contributions estimated?
  • How is pollutant load removal estimated?
  • What does the user need to input?
  • What can the user expect as outputs?
  • Considerations
  • Additional Features