Unnamed Thermal Spring

Mono County 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)
File:Casa Diablo IV geothermal (51874435703).jpg — public domain

At 7,313 feet elevation, this 72-degree thermal spring near Mammoth Lakes flows just 45 meters from El Camino Sierra Road in harsh alpine terrain where winter temperatures plunge well below freezing. The 28-degree temperature gain above ambient becomes particularly significant in this extreme climate.

The spring emerges in high Sierra Nevada country where massive granite peaks dominate the landscape. Cold alpine air descends from surrounding ridges, creating stark contrast with the warm thermal water rising from rocky ground. Dense lodgepole pine and whitebark pine scatter across volcanic terrain below jagged summits.

History of This Spring

This spring flows on lands managed by the Los Angeles Department of Water and Power, reflecting the Los Angeles Aqueduct system that diverts Eastern Sierra water to distant urban users. The spring's geothermal origin traces to ancient volcanic activity along the Sierra's eastern escarpment, where ongoing tectonic stress maintains thermal conditions.

Access is straightforward from nearby El Camino Sierra Road with minimal hiking. Winter snows exceeding 98 inches annually make November through April a serious backcountry challenge requiring proper winter gear. Summer and early fall provide ideal conditions for thermal soaking with alpine scenery.

Is this spring worth visiting?

Best for

  • Easy day trips
  • Overnight camping trips
  • Mineral-rich therapeutic bathing
This spring is well suited for easy day trips and overnight camping trips.
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
USGS Field Measurements
Recent Temperature 184.6°F (84.8°C) Measured Oct 04, 1983
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
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 →
What to Bring
Swimsuit & towel
Water bottle Stay hydrated, especially in hot water
Warm layers Cold air before and after soaking
Camping gear Nearby camping at Sherwin Creek
Trash bag Pack out what you pack in
References
USGS Quad: (MT. MORRISON 15) · Circ 790: 56.0 · NOAA: 12.0 · AMS Map: MARIPOSA
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.
Is it safe to soak at ?
is generally safe for soaking at its recorded temperature. Always tell someone your plans before visiting remote hot springs.
Is crowded?
is accessible from a paved road, making it easy to reach. Weekends and holidays may be busier — consider visiting on a weekday for a quieter experience.
What should I bring to ?
Essentials for : swimsuit, towel, water bottle, warm layers for before and after soaking, camping gear, a trash bag to pack out what you pack in.
Temperature
72°F
Warm Hot Boiling
Water Temp 72°F (22°C)
Avg Air Temp 44°F
Above Ambient +28°F
Good soaking conditions March
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