Map of Maryland's 12-Digit Watersheds

Please note that it may take several seconds for the map to load and refresh.

View Larger Map      Download Shapefile

About the Map

The shaded polygons in the map above represent Maryland’s 12-digit scale watersheds. The delineation breaks the state up into 1,100+ watersheds. Thus, these watersheds are smaller in size than the 8-digit scale watersheds and generally represent drainage divides between 2nd order rivers/streams. These watersheds are identified via a 12-digit numeric code. Watersheds in this polygon file relate to TMDLs and WLAs in the applicable queries via a 12-digit watershed name identified in the location description, if applicable (i.e., if the TMDL/WLA is developed at a 12-digit watershed scale).

Related Maps

Chesapeake Bay TMDL Map:  The 58 nitrogen TMDLs that comprise the Chesapeake Bay TMDL>

How to Use the Map

Clicking on a shaded polygon will display information about that 12-digit watershed, including the watershed name and ID.

To navigate the map, use your arrow to drag and pan. Click the plus and minus buttons to zoom in and out. Enter an address in the window (top right) to zoom to a location. Clicking on "Basemap" allows the user to change the background (e.g. aerial photography, topographic coverage, etc). Clicking on “View Larger Map” will take the user to a customizable map interface where additional layers may be added.

Please direct questions or comments concerning Maryland's TMDL Program to at (410) 537-3818.​​

Human Trafficking GET HELP

National Human Trafficking Hotline - 24/7 Confidential

1-888-373-7888 233733 More Information on human trafficking in Maryland

Customer Service Promise

The State of Maryland pledges to provide constituents, businesses, customers, and stakeholders with friendly and courteous, timely and responsive, accurate and consistent, accessible and convenient, and truthful and transparent services.

Take Our Survey

Help Stop Fraud in State Government

The Maryland General Assembly’s Office of Legislative Audits operates a toll-free fraud hotline to receive allegations of fraud and/or abuse of State government resources. Information reported to the hotline in the past has helped to eliminate certain fraudulent activities and protect State resources.

More Information