AUGUSTA — A city-owned camp on the shore of Three Cornered Pond is being used to help raise funds for Bicentennial Nature Park. Two weeklong stays at the camp are being raffled off to raise operating money for the city-run public park. The city acquired the two-bedroom camp when it bought the 27-acre site in 1997 to build the park, which features swimming and picnic areas. “The camp is used sparingly and only with the city manager’s permission,” said Leif Dahlin, city services director.