Welcome to the Watershed Management Modeling System, Los Angeles County’s most advanced platform for visioning future strategies to improve water quality, water supply and flood control. The Los Angeles County Flood Control District developed WMMS to allow for simulation of all the major watersheds within Los Angeles County including hydrologic and pollutant generation processes, transport routines, and forecasts of benefits that could be achieved by stormwater capture infrastructure and source control programs. WMMS is built upon two open source, USEPA-developed models – LSPC and SUSTAIN; learn more about WMMS on the About page.

The interactive map to the right shows the major elements of the LSPC model within WMMS 2.0 and allows for visualization of WMMS 2.0 outputs. The WMMS 2.0 configuration and calibration process incorporates:

• 3,117 square miles of model domain
• 2,500+ miles of explicitly modeled stream network
• 2,655 subwatersheds
• 4,066 ‘jurisheds’
• 662 precipitation nodes for weather boundary conditions
• 11 water reclamation plants
• 26 dams
• 26 spreading grounds
• 109 debris basins
• 23 stream diversions
• 34 hydrologic calibration stations, and
• 83 water quality calibration stations

To visualize the WMMS 2.0 simulation outputs, the time series for 40 'assessment points' across LA County have been extracted. Click on the assessment points (red flags) to view and download WMMS 2.0 outputs for a variety of hydrology and water quality simulations!