From Rock Creek Park NPS:
“August is National Fishing Month. In Rock Creek Park, fishing is only allowed downstream of the Porter Street Bridge and all angler’s must have a valid DC fishing license!”
I asked why the dividing line was at Porter and was told:
“we allow fishing south of Porter because Porter Street marks the southern boundary of Rock Creek Park (US Reservation 339). Our enabling legislation requires that we preserve all the natural and historic resources in the park. This includes the fish in the creek. However, south of Porter Street, there are no legislative restrictions on fishing (aside from the fact that any angler needs to have a valid District of Columbia fishing license).”
Side note: For those who’ve forgotten in 2017 the American Shad was officially designated as Washington, DC’s official fish.