Sulphur Works, Tophet Hot Springs

Plumas County, California · Near Chester
40.4470°N, 121.5360°W · 6,932 ft
199°F 6,932 ft Open Roadside National Park Service Camping nearby (5.8 mi)
Very Hot Source — Use Extreme Caution

At 199°F, the source water at Sulphur Works, Tophet Hot Springs is hot enough to cause burns. Some hot springs this hot have cooler side pools or downstream areas suitable for soaking — always test the water temperature before entering.

Sulphur Works and Tophet Hot Springs emerge at a dramatic 199°F at 6,932 feet elevation within Lassen Volcanic National Park, one of California's most spectacular geothermal displays accessible directly from the main park road.

Location

The springs produce intense geothermal activity visible from the roadside, with sulfurous steam rising from colorful mineral deposits in an alpine volcanic landscape shaped by recent geological upheaval and subject to winter snowfall exceeding 200 inches.

Roadside access from Lassen Peak Highway makes viewing accessible to all visitors. Winter closures occur due to heavy snowfall. Manzanita Lake Campground within the park sits 9.4 kilometers away and offers full facilities.

History of Sulphur Works, Tophet Hot Springs

These springs lie in Lassen Volcanic National Park, which protects one of the world's most active geothermal zones. The springs' mineral chemistry and water temperatures reflect recent magmatic activity beneath the peak.

Monthly Climate
29°
Jan
29°
Feb
32°
Mar
37°
Apr
45°
May
56°
Jun
65°
Jul
64°
Aug
57°
Sep
46°
Oct
35°
Nov
28°
Dec
Annual Precip: 45.7 in Annual Snow: 208.9 in
Best Time to Visit
December Air 28°F · Water 199°F · +171° contrast
January Air 29°F · Water 199°F · +170° contrast
February Air 29°F · Water 199°F · +170° contrast
December offers 36°F more contrast than August
Current Conditions
42°F
E 0.0 mph 87% Good soaking weather
Thursday 61° Low 43° Sunny 1% precip
Spring is +138° warmer
Friday 61° Low 42° Sunny
Spring is +138° warmer
Saturday 66° Low 42° Sunny
Spring is +133° warmer
Sunday 67° Low 46° Sunny
Spring is +132° warmer
Monday 67° Low 47° Mostly Sunny
Spring is +132° warmer
Water Chemistry Sampled 1981-06-30

The water at Sulphur Works, Tophet Hot Springs is slightly acidic (pH 6.1) with 88 mg/L total dissolved solids.

pH 6.1 Slightly Acidic
pH influences mineral absorption through skin
Higher mineral concentration for therapeutic soaking
Calcium 13 mg/L
May support bone density and joint health
Magnesium 2 mg/L
Known for muscle relaxation and stress relief
Sodium 4 mg/L
Supports circulation and skin hydration
Sulfate 25 mg/L
Traditionally used for skin conditions and inflammation
Chloride 0 mg/L
Natural antiseptic with skin health benefits
Where to Stay

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Nearby Camping
Manzanita Lake Group Campground 5.8 mi away

Overview Manzanita Lake Group Campground is located at the west end of Loop B in Manzanita Lake Campground, the largest campground in Lassen Volcanic National Park. It is within walking distance of scenic Manzanita Lake, a popular fishing and family destination, and offers impressive views of Lassen Peak, the largest volcano in the park at 10,457 feet.Recreation Manzanita Lake is popular with fly fishermen who enjoy the catch-and-release policy. Non-motorized boating is also permitted and kay...

Reservable Yes
Reserve on Recreation.gov →
Mile-High Advisory 6,932 ft

Sulphur Works, Tophet Hot Springs sits at 6,932 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
199°F
Warm Hot Boiling
Water Temp 199°F (93°C)
Avg Air Temp 44°F
Above Ambient +156°F
Great soaking conditions May
Access
Open
Road Access Roadside
Nearest Road Lassen Peak Highway
Distance to Road 180 ft
Land
Ownership Federal
Agency National Park Service
Designation National Park
Unit Lassen Volcanic National Park
Manager National Park Service
Protection 1 - Permanent protection, natural state
Frequently Asked Questions
What is the water temperature at Sulphur Works, Tophet Hot Springs?
Sulphur Works, Tophet Hot Springs has a water temperature of 199°F (93°C). This is considered a hot spring, well above body temperature.
Where is Sulphur Works, Tophet Hot Springs located?
Sulphur Works, Tophet Hot Springs is located in Plumas County, California at 6,932 feet elevation, near Chester. Coordinates: 40.4470°N, 121.5360°W.
How do I get to Sulphur Works, Tophet Hot Springs?
Sulphur Works, Tophet Hot Springs has Roadside road access, with the nearest road being Lassen Peak Highway (180 ft from the road).
Is Sulphur Works, Tophet Hot Springs free to visit?
Sulphur Works, Tophet Hot Springs has Open access. It is managed by National Park Service.
Can I camp near Sulphur Works, Tophet Hot Springs?
Yes, Manzanita Lake Group Campground is located nearby (5.8 miles away).
What minerals are in the water at Sulphur Works, Tophet Hot Springs?
Water chemistry analysis shows the presence of pH, Total Dissolved Solids, Calcium, Magnesium, Sodium, Sulfate, Chloride. The pH is 6.1 (slightly acidic). Total dissolved solids measure 88 mg/L.
Is it safe to soak at Sulphur Works, Tophet Hot Springs?
The water at Sulphur Works, Tophet Hot Springs reaches 199°F, which can cause severe burns. Do not enter the source pool directly — look for cooled side pools or downstream areas where the water has cooled to a safe temperature. Always tell someone your plans before visiting remote hot springs.
Is Sulphur Works, Tophet Hot Springs crowded?
Sulphur Works, Tophet Hot Springs 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 Sulphur Works, Tophet Hot Springs?
Essentials for Sulphur Works, Tophet Hot Springs: swimsuit, towel, water bottle, warm layers for before and after soaking, camping gear, a trash bag to pack out what you pack in. The water is over 110°F — test the temperature before entering and watch for scalding near the source.
Sources: USGS NWIS