Chesapeake Bay Watershed Model: Phase 5.3

Objective The Chesapeake Bay Watershed Model: Phase 5.3 (Bay Watershed Model) simulates the loading and transport of nitrogen, phosphorus and sediment from pollutant sources throughout the Chesapeake Bay watershed.

Developer The Bay Watershed Model was developed by USEPA and the Chesapeake Bay Program Office based on an application of the Hydrologic Simulation Program-Fortran (HSPF).

Contact information Gary Shenk,, 410-267-5745, Chesapeake Bay Program Office, 410 Severn Ave. , Suite 112, Annapolis, MD 21403

Inputs The Bay Watershed Model has an open source model code such that input data is freely available to the public. Input data includes precipitation information from USGS, municipal and industrial wastewater treatment and discharging facility data, atmospheric deposition from the Bay Airshed Model, land use data from the Bay Land Change Model, nutrient inputs from manure and fertilizers, as well as management actions are provided from the Scenario Builder tool.

Outputs The Bay Watershed Model provides estimates of watershed nitrogen, phosphorus and sediment loads to the tidal Chesapeake Bay resulting from various management scenarios.

User The Bay Watershed Model is used by USEPA and the Chesapeake Bay Program Office for the development and implementation of the Chesapeake Bay TMDL.

Scales of Relevance The Bay Watershed Model divides the Bay watershed into approximately 1,000 modeling segments/sub-basins with the average size of about 64 square miles. This is approximately equivalent to a USGS HUC 12 watershed scale.

Other The Bay Watershed Model is a community model which allows TMDL model developers, watershed researchers and implementation plan developers to use the model independently as is or as a starting point for more detailed, small-scale models.

Sponsors/funders USEPA and the Chesapeake Bay Program Office.