The California Office of Environmental Health Hazard Assessment (OEHHA) has formed a safe-eating advisory for fish caught in the lake, based on levels of mercury and PCBs found in local species.[7] Three of these streams contain acid mine drainage, with Spring Creek being the most notable contributor, releasing high concentrations of cadmium, copper and zinc into the water.Formed by the damming of the Sacramento River, the lake has 365 mi (587 km) of mostly steep mountainous shoreline covered with tall evergreen trees and manzanita.Also beneath the lake is the submerged town of Kennett and many village sites of the Wintun people together with their traditional fishing, hunting, and gathering locations.Shasta Lake has a hot-summer mediterranean climate (Csa) typical of the interior of Northern California with hot, dry summers and cool, wet winters, along with great diurnal temperature variation.