Unnamed Thermal Spring

Mono County, California · Near Mammoth Lakes
37.6530°N, 118.9250°W · 7,313 ft
72°F 7,313 ft Open Roadside CITY Camping nearby (1.8 mi)

An unnamed thermal point about four miles from Mammoth Lakes, Mono County, on ground belonging to the Los Angeles water and power department, LADWP. The water reads 72 degrees, tepid, cooler than a summer swimming pool. El Camino Sierra runs right past it. Access is open. Decades ago the USGS sampled the chemistry here.

Location

This is roadside in the plainest sense, about 150 feet from El Camino Sierra. The elevation is high, over seven thousand feet, and the record shows snowfall near eight feet in a typical winter on eighteen inches of precipitation. The landowner is the water utility of the city of Los Angeles.

Winter months top the list on file. Sherwin Creek campground is under two miles away. The chemistry shown dates to an old sample, with dissolved solids on the high side, so treat those figures as history. No fee is recorded and the land is open. At 72 degrees, this is wading water.

History of This Spring

A USGS site number is attached to this point, and the October 1983 water sample behind it supplies the pH and mineral readings shown on this page. The landowner is LADWP, the Los Angeles water and power department.

Terrain

Aircraft with laser scanners measured this ground to within inches. The scan strips out trees and buildings, leaving the bare shape of the land around this spring.

Aerial view of the ground around the spring LiDAR bare-earth view of the same ground around the spring
Aerial LiDAR bare earth

Drag the handle to compare the two views. The orange dot marks the spring, in a frame about three quarters of a mile wide.

Setting
Hillside
The spring sits on a steep slope that climbs to the west.
Highest ground nearby
375 ft above the spring
Within a quarter mile, to the west
Cross-section through the spring

A slice through the ground from west to east, about 0.6 miles end to end.

Elevation data: USGS 3D Elevation Program. Aerial imagery: USGS The National Map. Public domain.

Heat Below
140 milliwatts per square meter of heat flow

That's about twice the US average of 65. It's higher than at 89% of the springs on this site.

Heat flow measures the warmth working its way up through the ground from deep inside the earth. Where it runs high, rain and snowmelt that seep down through cracks in the rock come back up hot.

Heat flow estimate: Stanford Thermal Earth Model (Aljubran & Horne, 2024), CC BY 4.0.

Monthly Climate
28°
Jan
27°
Feb
32°
Mar
38°
Apr
46°
May
59°
Jun
66°
Jul
65°
Aug
58°
Sep
48°
Oct
36°
Nov
26°
Dec
Annual Precip: 18.3 in Annual Snow: 98.5 in
Best Time to Visit
December Air 26°F · Water 72°F · +46° contrast
February Air 27°F · Water 72°F · +45° contrast
January Air 28°F · Water 72°F · +44° contrast
December offers 40°F more contrast than July
Current Conditions
Today 74° Low 41° Sunny
Wednesday 70° Low 38° Sunny
Spring is +2° warmer
Thursday 70° Low 39° Sunny
Spring is +2° warmer
Friday 72° Low 42° Sunny
Saturday 74° Low 44° Sunny 1% precip
Water Chemistry Sampled 1983-10-04

The water at This spring is slightly alkaline (pH 7.5) with 1100 mg/L total dissolved solids. It is notably rich in sodium (supports circulation and skin hydration), chloride (natural antiseptic with skin health benefits), and total dissolved solids (higher mineral concentration for therapeutic soaking).

pH 7.5 Slightly Alkaline
pH influences mineral absorption through skin
Higher mineral concentration for therapeutic soaking
Calcium 2 mg/L
May support bone density and joint health
Magnesium 0 mg/L
Known for muscle relaxation and stress relief
Sodium 330 mg/L
Supports circulation and skin hydration
Sulfate 170 mg/L
Traditionally used for skin conditions and inflammation
Chloride 280 mg/L
Natural antiseptic with skin health benefits
Where to Stay

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Nearby Camping
Sherwin Creek 1.8 mi away

Overview Sherwin Creek Campground is located in the eastern Sierra Nevada Mountains within 2 miles of the full-service community of Mammoth Lakes, California. Popular among anglers, hikers, off-road vehicle enthusiasts and photographers, the campground is near some of the most spectacular wilderness and outdoor recreation areas in the Sierras.Recreation With a motocross track and trails, Sherwin Creek is a hot spot for off-road vehicle enthusiasts. The area's majestic scenery and challenging...

Reservable Yes
Reserve on Recreation.gov →
Mile-High Advisory 7,313 ft

this spring sits at 7,313 feet above sea level, way above the mile-high mark. You may not feel the altitude strongly, but hot water still dehydrates you faster at elevation. UV is about 29% stronger than at sea level, so bring sunscreen and drink more water than you normally would.

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Temperature
72°F
Warm Hot Boiling
Water Temp 72°F (22°C)
Avg Air Temp 44°F
Above Ambient +28°F
Mild soaking conditions September
Access
Open
Road Access Roadside
Nearest Road El Camino Sierra
Distance to Road 149 ft
Land
Ownership Local
Agency CITY
Designation LOTH
Unit Los Angeles Department of Water and Power
Manager CITY
Protection 4 - No known protection
Frequently Asked Questions
What is the water temperature at ?
has a water temperature of 72°F (22°C). This is a warm thermal spring.
Where is located?
is located in Mono County, California at 7,313 feet elevation, near Mammoth Lakes. Coordinates: 37.6530°N, 118.9250°W.
How do I get to ?
has Roadside road access, with the nearest road being El Camino Sierra (149 ft from the road).
Is free to visit?
has Open access. It is managed by CITY.
Can I camp near ?
Yes, Sherwin Creek is located nearby (1.8 miles away).
What minerals are in the water at ?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride. The pH is 7.5 (slightly alkaline). Total dissolved solids measure 1,100 mg/L.
Sources: USGS NWIS