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Every Hot Spring

Sulphur Works, Tophet Hot Springs

Sulphur Works, Tophet Hot Springs is a geothermal spring near Mineral in California. Water at the source is recorded at 199°F (93°C), hot enough to scald. It is documented as closed to soaking and is listed for reference only.

199°F93°C recorded at the source
Scalding at the source. Do not enter without a cooled, mixed pool.

Sulphur Works is a roadside hydrothermal area of boiling springs, mudpots and fumaroles inside the caldera of Mount Tehama in Lassen Volcanic National Park. It is a protected park feature; soaking is not possible.

Facts

Coordinates
40.4470, -121.5360 (Google Maps, OSM)
Source temperature
199°F (93°C)
Access
Public land
Type
Unknown
Fee
Not recorded
Clothing optional
Not recorded
Nearest town
Mineral
Data sources
NOAA NCEI, Official sources (linked below). See sources

Map

Larger marker is Sulphur Works, Tophet Hot Springs; smaller markers are other springs within 50 miles.

Quick answers

Can you soak at Sulphur Works, Tophet Hot Springs?
No. Sulphur Works, Tophet Hot Springs is documented as closed to soaking or off-limits to bathing. It is listed for reference only; see the sources on this page.
How hot is Sulphur Works, Tophet Hot Springs?
The hottest recorded reading at the source is 199°F (93°C). That is the outlet temperature, not a pool temperature; water cools as it flows away from the source. Water this hot can cause serious burns, so test any pool by hand first.
Where is Sulphur Works, Tophet Hot Springs?
Sulphur Works, Tophet Hot Springs is near Mineral in California, at coordinates 40.4470, -121.5360.
What other hot springs are near Sulphur Works, Tophet Hot Springs?
The closest listed springs, in straight-line distance, are Sulphur Works, under 1 mi; Mill Creek Springs, under 1 mi; and Bumpass Hell, 2 mi.

Before you go

  • Temperatures are measured at the source and can be far hotter than any soaking pool. Test with a hand before stepping in.
  • Access, fees, and road conditions change. Verify with the land manager or owner; "public" here reflects survey records, not a current right of entry.
  • Water in natural springs is untreated. Keep your head above water and avoid soaking with open wounds. Some springs carry Naegleria fowleri risk.
  • Pack out everything, including soap residue. Many springs have been closed because of trash and overcrowding.

Sources

Dataset last rebuilt October 11, 2026. Not yet checked on site by a person. Access, fee, clothing and closure details appear only when a source below states them. How this data is built.

Checked against

  1. Wikipediaen.wikipedia.org/wiki/Geothermal_areas_in_Lassen_Volcanic_N…

Merged from

  1. NOAA NCEI Thermal Springs List (archived 2025): survey location and source temperature, public domain