Moraine State Park is a Pennsylvania state park on 16,725 acres (6,768 ha) in Brady, Clay, Franklin, Muddy Creek, and Worth townships in Butler County, Pennsylvania, in the United States. The main feature of the park is its man-made lake, Lake Arthur, formed by impounding Muddy Creek, which is 3,225 acres (1,305 ha) and is used for recreational purposes. The surrounding park is used for hiking, bicycling, group camping, picnicking, and hunting. Moraine State Park hosts the annual Regatta at Lake Arthur in August. The park served as the location of the 1973 and 1977 National Scout Jamborees. Moraine State Park is at the intersection of Interstate 79 and U.S.