From an email:
“I wanted to let you know Rock Creek Conservancy will host volunteer events across the Rock Creek watershed this Saturday, Jan. 14 and Monday, Jan. 16 in honor of MLK Day. Our goal is to pick up trash in and around Rock Creek and its tributaries and remove invasive exotic plants from park lands.
We have a neat interactive map on our website here that allows people to find a volunteer event near them (and a complete listing of events is also on that page).”