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Patapsco River

Watershed Management Program
Phone: 410-887-5683
Fax: 410-887-4804


This is a map showing the location of the Patapsco River watershed.

The Patapsco River Watershed is located in the southwestern portion of Baltimore County. It is bounded by the Liberty Reservoir and Carroll County line to the north, the Patapsco River and Howard County line to the west, and the Anne Arundel and Baltimore City lines to the south. The watershed includes the communities of Catonsville, Arbutus and Halethorpe. It also includes the University of Maryland at Baltimore County, Catonsville Community College and the Patapsco Valley State Park.

While the Patapsco River is a minor river for most of its length, its last 10 miles are a large tidal estuary inlet of Chesapeake Bay. The tidal area of the Patapsco, comprised of the Northwest Harbor and Middle Branch, is crossed by the Baltimore Harbor and Fort McHenry Tunnels as well as the Francis Scott Key Bridge.

The watershed is home to Patapsco Valley State Park which extends along 32 miles of the Patapsco River, encompassing 14,000 acres and five developed recreational areas. Recreational opportunities include hiking, fishing, camping, canoeing, horseback and mountain bike trails, as well as picnicking for individuals or large groups in the park's many popular pavilions. The watershed provides good habitat for many species of fish including smallmouth bass, rock bass, redbreast sunfish, hog suckers and white suckers.

Small Watershed Action Plan

A small watershed action plan (SWAP) identifies strategies to bring a small watershed into compliance with water quality standards and goals developed by stakeholders in the watershed. Strategies go beyond traditional government capital projects and include actions in partnership with local watershed associations, citizen awareness campaigns and volunteer activities.

Upper Patapsco SWAP

A SWAP for the Upper Patapsco (PDF) planning area has been completed and includes the area of Granite and part of Randallstown.

Lower Patapsco SWAP

A SWAP has been completed for the Lower Patapsco planning area. This plan covers the area from Catonsville to Arbutus.

  • Volume I (PDF) outlines the actions identified as part of the strategy.    
  • Volume II (PDF) contains the results of the field and GIS data assessments.


To participate as a volunteer for the Patapsco River watershed, contact the Patapsco Heritage Greenway.

Revised July 27, 2021         


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