Potomac River Basin Study Unit
- Part of the U.S. Geological Survey (USGS) sponsored National Water-Quality Assessment (NAWQA) Program. Features reports and articles.
- http://md.water.usgs.gov/pnawqa/

GORP: Potomac Basin
- Guide to the Potomac River Basin hiking, biking, camping, climbing and other outdoor activities.
- http://gorp.away.com/gorp/location/md/ru_poto.htm

Potomac River Guide
- Information and history of the Potomac River. Features links to other Potomac River sites.
- http://www.riverexplorer.com/

The Potomac Conservancy
- A land trust dedicated to preserving the scenic and natural Potomac River.
- http://www.potomac.org/

Interstate Commission on the Potomac River Basin
- Working to enhance, protect and conserve the water quality and associated land resources of the Potomac River basin and its tributaries through regional and interstate cooperation. Includes strategic plan, water quality, projects, and news.
- http://www.potomacriver.org/

Bridging the Watershed
- A National Parks Labs program to promote national parks in the Potomac watershed as learning laboratories for secondary teachers and students.
- http://www.bridgingthewatershed.org/