The river divides the Capital Wasteland in half. Some portions have dried up, and the water that exists is radioactive. There are boats in the river both above the surface and below the water line containing ammunition and first aid boxes. Mirelurks are often found in and around it, with mirelurk hunters and mirelurk kings found at higher levels.
- Jameson Grillo and Aaron Bradie left a message on the Shelters Claim Center terminal that they were having trouble finding food and planned on following the Potomac south toward a warmer climate.
- Leroy Walker comments that since he can't burn pennies, he will instead throw them into the Potomac.
- The Potomac is mentioned in the Republic of Dave tour.
- Lucy West: "Arefu is northwest of Megaton on an old overpass over the Potomac. If you follow what's left of the river, you can't miss it."
(Lucy West's dialogue)
- Shelters Claim Center terminal entries; Communications Logs; Re: Moving on - 12/01/2077
- Leroy Walker: "Hmm. Can't burn pennies. I'll have to toss them into the Potomac."
(Leroy Walker's dialogue)
- Shawna: "Dave is a world-renowned marksman, known for shooting an apple out of the hand of a Raider from across the Potomac."