Lake Bernard Frank (Lake Frank), is a 54-acre (220,000 m2) reservoir on the North Branch of Rock Creek in Derwood, Maryland, U.S., just east of Rockville. It is named after Bernard Frank, a wilderness activist and a co-founder of The Wilderness Society. The lake's boundaries are, approximately, Route 28, East Gude Drive, Avery Road, and Muncaster Mill Road.