the McMillan Recreation building (on the Reservoir side, not the Sand Filtration side)

See these tweets:

#BloomingdaleDC (I have submitted a comment to advise that this building is extant. https://t.co/POGEV3j2zB

— Bloomingdame (@bloomingdame) September 15, 2017

#BloomingdaleDC/McMillan Recreation building still stands w/i Reservoir fence. Interior condition unknown Attn: @McMillanPark @KentBoeseDC pic.twitter.com/6Ercb1JdHM

— Bloomingdame (@bloomingdame) September 15, 2017

Don't think the Recreation building is specifically mentioned in the McMillan Park Reservoir Historic District nom https://t.co/KTVwyHV3fv

— Bloomingdame (@bloomingdame) September 15, 2017