GIS Resources

Watershed Boundary Shapefiles

These files delineate various boundaries that are used for Chesapeake Bay Program/EPA modeling. It is important to note that some of the accuracy of the Bay model data degrades at the smaller scales and the complexity of Phase II WIP strategy development increases.  Our general recommendation to WIP local teams is to plan at the County / Major-Basin scale when working with the Maryland Assessment and Scenario Tool (MAST) provided by the State.  However, in some situations planning at a more specific scale makes sense, such as for municipalities and federal facilities, targeting septic system upgrades near tidal waters and other cases.

Click here for zip file containing GIS shapefiles that delineate the following:

  • Land-River Segment boundaries - The smallest boundary delineated
  • Segment-Shed boundaries - TMDL boundaries
  • County Segment-Shed boundaries - Segment-shed intersected with County Boundaries
  • Major Basin Boundaries - The five major watersheds in Maryland for which EPA provided State allocations that meet Bay water quality targets.


Federal Boundary Shapefiles

These files delineate various applicable federal shapefiles for Maryland.

The zip file contains the following GIS shapefiles:

  • MD federal land-river segments
  • Original data from EPA containing information on federal ownership (MD area only)
  • Refined data with federal ownership used to inform federal allocations (MD area only)
  • MDE Urban BMP Database - Reported State and Federal BMPs
  • Extracted Federal BMPs


Chesapeake Bay Program Website

The Chesapeake Bay Program WIP Tools website provides shapefiles for download. These shapefiles include Relative Effectiveness and Federal Lands. These files are periodically updated so it is important to check the website.


Contact Information

Please direct questions or comments to Jim George at (410) 537-3579.

Other Helpful Links 

Phase II WIP Development Support Page​​