Hilltop Hot Spring

Also known as: Alkali Hot Springs
Mono County, California · Near Mammoth Lakes
37.6670°N, 118.7810°W · 6,880 ft
127°F 37°F air · Good soaking weather 6,880 ft Open Roadside Bureau of Land Management Camping nearby (6.8 mi)

Hilltop Hot Spring, which OpenStreetMap lists as Alkali Hot Springs, is BLM ground near Mammoth Lakes, around twelve miles out, in Mono County. Access is listed as open. The source runs hot, above body temperature by a wide margin, and the water carries a heavy mineral load. Iron and sulfate both turned up in sampling. There is a photo.

Location

Benton Crossing Road passes within a few dozen feet, so this is a pull-over spot. No walking involved. The Bishop Field Office manages the land. Seven thousand feet up, give or take, winters bring real snow, though the year as a whole is dry. Crowley Lake Campground is about seven miles distant.

Open public land, no fee on record. Winter ranks top for timing in the row, and with six feet of snow in an average year the road may decide for you. The source itself is too hot to soak in straight, so find out where the water has cooled first. Chemistry was sampled in 1990 and may have drifted since.

History of Hilltop Hot Spring

OpenStreetMap carries a second name, Alkali Hot Springs. The USGS site here was sampled in January 1990.

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 Hilltop Hot Spring.

Aerial view of the ground around Hilltop Hot Spring LiDAR bare-earth view of the same ground around Hilltop Hot 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
Open ground
Flat, open ground all around.
Highest ground nearby
29 ft above the spring
Within a quarter mile, to the north
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
127 milliwatts per square meter of heat flow

That's about twice the US average of 65. It's higher than at 78% 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
30°
Jan
29°
Feb
34°
Mar
41°
Apr
49°
May
62°
Jun
68°
Jul
67°
Aug
61°
Sep
50°
Oct
39°
Nov
29°
Dec
Annual Precip: 14.4 in Annual Snow: 72.3 in
Best Time to Visit
February Air 29°F · Water 127°F · +98° contrast
December Air 29°F · Water 127°F · +98° contrast
January Air 30°F · Water 127°F · +97° contrast
February offers 39°F more contrast than July
Current Conditions
37°F
Clear WNW 25.0 mph 48% Good soaking weather
Tuesday 78° Low 40° Sunny
Spring is +49° warmer
Wednesday 75° Low 38° Sunny
Spring is +52° warmer
Thursday 75° Low 37° Sunny
Spring is +52° warmer
Friday 75° Low 38° Sunny
Spring is +52° warmer
Saturday 77° Low 40° Sunny 1% precip
Spring is +50° warmer
Water Chemistry Sampled 1990-01-10

The water at Hilltop Hot Spring is neutral (pH 7.0) with 1260 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 7.0 Neutral
pH influences mineral absorption through skin
Higher mineral concentration for therapeutic soaking
Calcium 24 mg/L
May support bone density and joint health
Magnesium 1 mg/L
Known for muscle relaxation and stress relief
Sodium 370 mg/L
Supports circulation and skin hydration
Sulfate 64 mg/L
Traditionally used for skin conditions and inflammation
Chloride 150 mg/L
Natural antiseptic with skin health benefits
Iron 190 µg/L
Iron-rich springs may support circulation
Where to Stay

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Nearby Camping
Crowley Lake Campground 6.8 mi away

Overview Crowley Lake Campground offers 47 RV/tent sites, maximum recommended RV length is 30 feet. All sites include a fire pit, picnic table and a lantern holder. No hook-up. Potable water is available. Dump station fee is $10.00, no passes accepted. Closest amenities are 2 miles south in Crowley, or 10 miles north in Mammoth Lakes. Recreation Popular activities include lake and stream fishing, boating, windsurfing, horseback riding, hiking, and wildlife viewing. Facilities Crowley Lake...

Reservable Yes
Reserve on Recreation.gov →
Mile-High Advisory 6,880 ft

Hilltop Hot Spring sits at 6,880 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 28% stronger than at sea level, so bring sunscreen and drink more water than you normally would.

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Temperature
127°F
Warm Hot Boiling
Water Temp 127°F (53°C)
Avg Air Temp 47°F
Above Ambient +80°F
Great soaking conditions September
Access
Open
Road Access Roadside
Nearest Road Benton Crossing Road
Distance to Road 55 ft
Bath Type Hot spring
Land
Ownership Federal
Agency Bureau of Land Management
Designation PUB
Unit Bishop Field Office
Manager Bureau of Land Management
Protection 3 - Protected, subject to extractive use
Frequently Asked Questions
What is the water temperature at Hilltop Hot Spring?
Hilltop Hot Spring has a water temperature of 127°F (53°C). This is considered a hot spring, well above body temperature.
Where is Hilltop Hot Spring located?
Hilltop Hot Spring is located in Mono County, California at 6,880 feet elevation, near Mammoth Lakes. Coordinates: 37.6670°N, 118.7810°W.
How do I get to Hilltop Hot Spring?
Hilltop Hot Spring has Roadside road access, with the nearest road being Benton Crossing Road (55 ft from the road).
Is Hilltop Hot Spring free to visit?
Hilltop Hot Spring has Open access. It is managed by Bureau of Land Management.
Can I camp near Hilltop Hot Spring?
Yes, Crowley Lake Campground is located nearby (6.8 miles away).
What minerals are in the water at Hilltop Hot Spring?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 7.0 (neutral). Total dissolved solids measure 1,260 mg/L.
Is it safe to soak at Hilltop Hot Spring?
With care. At 127°F Hilltop Hot Spring is hot enough to need short sessions, fifteen to twenty minutes, and plenty of water. Enter slowly and get out if you feel light-headed.