By Susan Soderberg
Families picnicking, children cavorting on the playgrounds, teens paddling around the lake in kayaks and fishermen dropping their lures hoping for a bite, summer is here at Black Regional Hill Park. Black Hill and Little Seneca Lake, forming the northern border of Germantown, is a well-used recreational area, especially on these hot summer days. But the lake was not created only for having fun. It is an emergency water supply for the Washington Suburban Sanitary Commission, the Washington Aqueduct, and the Fairfax County Water Authority in Virginia.