Photo by PoPville flickr user clif_burns
Thanks to @Mr_Darling for finding out:
“Just got got confirmation [fountains at Meridian Hill Park to be turned off for the season] it’s the week of September 16th.”
This year the fountains got filled slightly later than in previous years due to budget constraints. And in previous years the fountains have remained filled until November. So unfortunately this is the last weekend to enjoy the great view until next year!