The Shasta-Trinity National Forests are federally designated forests in northern California, United States. Combined, they are the largest National Forest in California and are managed by the U.S. Forest Service. The 2,210,485 acre (894,552 Ha) combined-forest encompasses five wilderness areas, hundreds of mountain lakes and of streams and rivers. Major features include Shasta Lake, the largest man-made lake in California and Mount Shasta, elevation .