 The water in Lake Natoma, which is the lake created by Nimbus Dam, is too cold for warmwater production of fish, and never has the lake been a natural producer of fish.The rapid water exchange from Nimbus Dam sharply decreases the production of plankton, which inhibits trout growth.The Department of Fish and Game annually plants Lake Natoma with 20,000 to 30,000 catchable-sized trout.