1995, the annual Winter Lights Festival has featured a drive-through holiday light show at year's end in the Clopper Lake Day Use Area. Historic sites The remains of Seneca Quarry, built in 1837, is off Tschiffely Mill Road just west of where Seneca Creek empties into the Potomac. The mill cut the red sandstone for the Smithsonian Castle. The restored quarry masters house stands above the quarry site. Both are part of the state park. The partially restored Black Rock Mill has interpretive exhibits featuring a history of area floods. The Seneca Schoolhouse is a restored 19th-century schoolhouse which was built for the children of local quarry laborers. Parts of the park were once part of an estate owned by the Clopper family. The Woodlands area near the Clopper Lake Day Use Area commemorates the Clopper family with a self-guided trail that offers a look into life in the 19th century. In popular culture The Blair Witch Project was partially filmed in the Seneca Creek State Park in October of 1997, and the rock band O.A.R. referenced the park in the song "Black Rock" on their 1997 album The Wanderer. References External links Seneca Creek State Park Maryland Department of Natural Resources Seneca Creek State Park Map Maryland Department of Natural Resources State parks of Maryland Parks in Montgomery County, Maryland Potomac River watershed Protected areas established in 1958 1958 establishments in Maryland