The primary surface watercourse in the Mammoth hydrologic basin and a major feeder to the Upper Owens River, Mammoth Creek drains the numerous lakes, streams and snow fields of the Lakes Basin, as well as Valentine and Sherwin lakes and the southeastern flanks of Mammoth Mountain. Meandering through the heart of Old Mammoth, the creek flows down valley to the east, across Highway 395, to its confluence with Hot Creek.