Lake Thomas A Edison
Lake · 7,647 ft · Mammoth Lakes corridor
Lake Thomas A Edison sits at 7,647 feet in the Mammoth Lakes corridor, a high-Sierra reservoir fed by snow melt and glacial runoff. Wind funnels across the open water by afternoon most days.
Morning calm gives way to afternoon wind off the eastern Sierra ridgeline. The 30-day average wind of 8 mph masks afternoon gusts near 20 mph. Water stays cold year-round; expect exposed conditions and rapid weather swings. Sheltered coves are warmer and slower than the main body.
The last 30 days averaged a NoGo Score of 12, with temperatures hovering at 35 degrees and wind averaging 8 mph. Afternoon gusts regularly reach 20 mph. The week ahead shows typical spring variability; plan morning sessions and watch for rapid wind onset after 10 AM.
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About Lake Thomas A Edison
Lake Thomas A Edison lies in the high-Sierra drainage east of the Mammoth crest, accessible via Highway 168 from the town of Mammoth Lakes. The reservoir sits on the South Fork San Joaquin River system and serves as a lower-elevation alternative to the alpine lakes scattered across the range to the west. Drive time from Mammoth Lakes is roughly 45 minutes. The lake occupies a glacially scoured valley with steep granite walls on three sides; the eastern shore is more open. Parking is available at the main boat launch and at pullouts along the western shore access road.
Water temperature ranges from 35 to 55 degrees over the year, coldest in spring when snowmelt is heaviest and warmest in late summer. Wind is the dominant constraint. The 30-day average wind of 8 mph masks strong diurnal cycles; calm mornings are routine, but afternoons almost always see 15 to 20 mph gusts funnel across the lake from the northwest. Crowds are light compared to Mammoth Lakes basin proper; the 30-day average crowding score of 4 reflects mid-week and shoulder-season visits. Weekends draw modest crowds, especially if the lake access road is fully open. Snow typically closes or restricts access in winter and early spring.
Lake Thomas A Edison suits anglers, paddlers, and swimmers seeking high-Sierra conditions without the Mammoth Lakes basin crowds. Fishing pressure is steady but never overwhelming; the reservoir holds brook and rainbow trout. Kayakers and stand-up paddleboarders plan for morning windows; afternoon wind makes the crossing hazardous for smaller craft. The lake is cold enough year-round that thermal protection is mandatory for water activities. Afternoon winds and rapid gusts mean afternoon trips suit experienced paddlers only. Motorized boats are allowed and common, so expect some traffic during peak season weekends.
Nearby alternatives include Crowley Lake to the north, which is larger and more exposed to afternoon wind but closer to Mammoth village. Convict Lake to the west offers a smaller, more sheltered alternative with similar trout fishery and stronger afternoon wind character. The South Fork drainage continues upstream past Thomas A Edison toward Mono Creek and the wilderness beyond, offering backcountry access for those with permits and daylight tolerance. Rock Creek, just east via Highway 395, provides a parallel high-Sierra canyon with fishing and camping options.