Who knew? It cannot have been the full Die Walküre, as that would need to start much earlier than 7:30pm. It was given as a pantomime by a grils' summer camp with JB playing the piano score. Otsego Lake is a lake located in Otsego County in the U.S. state of New York. It is the source of the Susquehanna River and largest lake in Otsego County. The Village of Cooperstown is located at the lake's southern end. Glimmerglass State Park is located on the lake's northeastern shore