DCnative who attended DCPS& PGC schools and i just learned this at my big age earlier this week
The Secret Reason D.C. Has No Beach At The Tidal Basin
Tidal Basin Beach History That Got Erased
On This Day In DMV History, February 18, 1925, Congress Shut Down The Tidal Basin Bathing Beach After A Blowup Over Segregation. 
Dustinmfox