Brooks Warm Spring

Fergus County County, Montana · Near Lewistown
47.2170°N, 109.4710°W · 3,795 ft
68°F 3,795 ft Short Walk
Brooks Warm Spring
File:M 4710953 nw 12 060 20210616.tif — public domain

Brooks Warm Spring emerges at a mild 68°F in central Montana, requiring a short walk of about 998 meters from the nearest road. USGS data confirms a temperature of 19.6°C. The water is calcium-sulfate dominant, with 130 mg/L calcium, 330 mg/L sulfate, and total dissolved solids of 659 mg/L at near-neutral pH 7.4.

The spring rises at 3,795 feet in the prairie-mountain transition zone of Fergus County, south of Lewistown. Rolling grassland and scattered timber mark the landscape where the Judith Mountains and Big Snowy Mountains interrupt the plains. The terrain is open rangeland with seasonal creeks cutting shallow coulees. Annual precipitation reaches 21 inches, with 53 inches of snowfall, creating green-up conditions in spring that brown out by midsummer across the surrounding benchlands.

History of Brooks Warm Spring

Little published history documents this spring specifically. The name likely references an early settler or rancher in the area. The Lewistown vicinity attracted homesteaders in the early 1900s who relied on local water sources. The spring's calcium-rich, sulfate-heavy chemistry suggests deep circulation through Paleozoic limestone and gypsum beds that underlie much of central Montana's sedimentary terrain.

The spring is too cool for hot-soaking but supports an interesting thermal-biological environment. Visit in late spring or early summer when access roads are dry and the surrounding hills are green. Bring water and sun protection, as the open prairie offers little shade. The nearest town, Lewistown, sits roughly 20 miles north and provides all services. No permits are currently required.

Monthly Climate
25°
Jan
23°
Feb
34°
Mar
41°
Apr
52°
May
61°
Jun
70°
Jul
69°
Aug
59°
Sep
44°
Oct
33°
Nov
25°
Dec
Annual Precip: 21.2 in Annual Snow: 53.5 in
Best Time to Visit
February Air 23°F · Water 68°F · +45° contrast
January Air 25°F · Water 68°F · +43° contrast
December Air 25°F · Water 68°F · +43° contrast
February offers 47°F more contrast than July
USGS Field Measurements
Recent Temperature 67.3°F (19.6°C) Measured Jun 29, 1977
Water Chemistry Sampled 1977-06-29

The water at Brooks Warm Spring is slightly alkaline (pH 7.4) with 659 mg/L total dissolved solids. It is notably rich in calcium (may support bone density and joint health), magnesium (known for muscle relaxation and stress relief), and sulfate (traditionally used for skin conditions and inflammation).

pH 7.4 Slightly Alkaline
pH influences mineral absorption through skin
Higher mineral concentration for therapeutic soaking
Calcium 130 mg/L
May support bone density and joint health
Magnesium 40 mg/L
Known for muscle relaxation and stress relief
Sodium 4 mg/L
Supports circulation and skin hydration
Sulfate 330 mg/L
Traditionally used for skin conditions and inflammation
Chloride 2 mg/L
Natural antiseptic with skin health benefits
Iron 30 µg/L
Iron-rich springs may support circulation
What to Bring
Swimsuit & towel
Water bottle Stay hydrated, especially in hot water
Warm layers Cold air before and after soaking
Trash bag Pack out what you pack in
References
USGS Quad: LEWISTOWN 15 · PP 492: 10.0 · NOAA: 1.0 · AMS Map: LEWISTOWN
Frequently Asked Questions
What is the water temperature at Brooks Warm Spring?
Brooks Warm Spring has a water temperature of 68°F (20°C). This is a warm thermal spring.
Where is Brooks Warm Spring located?
Brooks Warm Spring is located in Fergus County, Montana at 3,795 feet elevation, near Lewistown. Coordinates: 47.2170°N, 109.4710°W.
How do I get to Brooks Warm Spring?
Brooks Warm Spring has Short Walk road access (0.6 mi from the road).
What minerals are in the water at Brooks Warm Spring?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride, Iron. The pH is 7.4 (slightly alkaline). Total dissolved solids measure 659 mg/L.
Is it safe to soak at Brooks Warm Spring?
Brooks Warm Spring is generally safe for soaking at its recorded temperature. Access may be on private land or unconfirmed — verify current conditions before visiting. Always tell someone your plans before visiting remote hot springs.
Is Brooks Warm Spring crowded?
Brooks Warm Spring sees varying levels of visitors depending on the season and day of the week.
What should I bring to Brooks Warm Spring?
Essentials for Brooks Warm Spring: swimsuit, towel, water bottle, warm layers for before and after soaking, a trash bag to pack out what you pack in.
Temperature
68°F
Warm Hot Boiling
Water Temp 68°F (20°C)
Avg Air Temp 45°F
Above Ambient +23°F
Good soaking conditions March
Access
Road Access Short Walk
Distance to Road 0.6 mi