We've been there before. Today we went for our first picnic with fellow kazakhs living in DC metro area.
The weather forecast wasn't very good, but actual weather was. At least, until we stayed there.
It's a nice place with a little but beautiful waterfall. There's a picnic area with approximately 50 tables and 17 grills. We came early at 11am. It's a good idea to come before it gets crowder afternoon.