Lake Thomas A Edison is a reservoir in the Sierra National Forest and in Fresno County, California. It is in the Sierra Nevada, and near the Pacific Crest Trail.The reservoir's waters are impounded by Vermilion Valley Dam, which was completed in 1954. The reservoir and dam are part of the Big Creek Hydroelectric Project.HydrologyThe reservoir discharges into Mono Creek, a tributary of the South Fork San Joaquin River. However, some of its water is diverted to Huntington Lake by means of the Ward Tunnel.Vermilion Valley DamVermilion Valley Dam is an earthen dam long and high, with of freeboard. Southern California Edison owns the dam.RecreationLocated in Sierra National Forest near the Pacific Crest Trail, Lake Thomas A Edison is the centerpiece of Vermilion Valley Resort and Vermillion Campground, which support boating, camping, fishing, swimming, canoeing, kayaking, and horseback riding.AccessThe lake is three hours by car from Fresno. Take State Route 168 east to Huntington Lake, head east on Kaiser Pass Road. The road crosses Kaiser Pass (elevation ) and closes during the winter months. The United States Forest Service does not recommended it for buses, large motor homes, or vehicles towing trailers.