Maps Potomac River Basin Drinking Water Source Protection Partnership Potomac Watershed Map with Streams Sub-watersheds of the Potomac River Land Use Map-2006 Data 1997 Land Use Map Washington Metro Water Supply Service Areas (as of 2010) USGS Potomac Watershed Stream Gages Harmful Algal Bloom (HAB) Monitoring Locations Additional maps are available from the Interstate Commission on the Potomac River Basin.
