MGSFlood is a general, continuous, rainfall-runoff computer model developed specifically for stormwater facility analysis and meets the requirements of the 2012 Washington State Department of Ecology Stormwater Management Manual for Western Washington. The program includes routines for sizing LID facilities, stormwater detention, and water quality treatment. The program comes preloaded with precipitation and evaporation time series for western Washington and also allows for input of user defined precipitation.


  • Drag and Drop Graphical Interface,
  • Computes Facility Flow Duration Compliance per the 2012 Ecology Manual
  • Extended 5-minute precipitation time series for most of Puget Sound and the City of Seattle suitable for conveyance design,
  • “Single Click” pond and infiltration trench sizing and Optimization routine,
  • GSI Simulation, Including Bio-Retention, Green Roof, and Porous Pavement
  • Simulation of stream channels with complex shapes, including floodplains,
  • Routines for performing Wetland Hydroperiod Analyses,
  • Computes Water Quality Treatment Design Parameters (Volume and Discharge rate)
  • Routines for Computing and Graphing Streamflow frequency, duration statistics, and hydrographs
  • Exports storm hydrographs to routing programs such as SWMM Extran
  • Seasonal Flood Frequency and Duration Statistics Useful for Construction Management

MGSFlood Main Program Interface

MGSFlood Graphical Interface for Large Complex Watershed