Sulfate

The signature of traditional "sulfur springs."

What it is

Sulfate is a sulfur-oxygen ion. When sulfate is reduced to hydrogen sulfide underground, it gives some springs the familiar "rotten egg" smell. Sulfur springs have been used for skin and joint conditions for centuries.

In hot springs

Sulfate varies widely, from a few mg/L to several hundred. Springs high in sulfate or hydrogen sulfide are the classic "sulfur springs" of balneology.

Cited benefits and context

A 2022 multicenter randomized trial evaluated thermal spa therapy for plaque psoriasis and found benefit as an add-on treatment (Evaluation of the benefit of thermal spa therapy in plaque psoriasis, Springer 2022). A 2024 review covers balneotherapy for dermatological disease more broadly (Springer, 2024).

The WHO notes that sulfate in drinking water above roughly 250 mg/L can have a laxative effect, along with a noticeable taste (WHO Guidelines for drinking-water quality). That is an ingestion concern and does not apply to soaking. Evidence for transdermal sulfur is limited, though traditional use in psoriasis and arthritis has some RCT support for spa therapy overall.

Cautions

A faint hydrogen sulfide odor is common at sulfur springs and generally not harmful at low levels, but it indicates reducing conditions. Do not drink high-sulfate spring water.

Springs ranked by most sulfate

179 springs with verified sulfate data · showing top 50 · source: USGS Water Quality Portal

  1. 1

    The Landusky Plunge

    mt · 77°F · primitive

    2600 mg/L

  2. 2

    Brockman Creek Hot Spring

    id · 102°F · primitive

    2500 mg/L

  3. 3

    Big Spring

    id · 85°F · primitive

    1500 mg/L

  4. 4

    Alpine Warm Spring

    id · 85°F · primitive

    1000 mg/L

  5. 5

    Bear Lake Hot Springs

    id · 102°F · developed

    800 mg/L

  6. 6

    Heise Hot Springs

    id · 102°F · developed

    740 mg/L

  7. 7

    White Licks Hot Spring

    id · 102°F · primitive

    660 mg/L

  8. 8

    Bald Mountain Hot Springs

    id · 115°F · primitive

    653 mg/L

  9. 9

    Hot Springs State Park

    wy · 104°F · primitive

    650 mg/L

  10. 10

    Mammoth Hot Springs

    wy · 162°F · developed

    411 mg/L

  11. 11

    Deer Hot Springs

    id · 102°F · primitive

    360 mg/L

  12. 12

    Alkali Flats Warm Spring

    id · 85°F · primitive

    340 mg/L

  13. 13

    Yandell Springs

    id · 102°F · primitive

    330 mg/L

  14. 14

    Cleveland Hot Springs

    id · 102°F · primitive

    322 mg/L

  15. 15

    Pincock (Green Canyon) Hot Springs

    id · 102°F · primitive

    320 mg/L

  16. 16

    Goldbug Hot Springs

    id · 136°F · primitive

    300 mg/L

  17. 17

    Rock Creek Hot Springs

    mt · 112°F · primitive

    300 mg/L

  18. 18

    Yellowstone Hot Springs

    mt · 104°F · resort

    294 mg/L

  19. 19

    Riggins Hot Springs

    id · 102°F · primitive

    290 mg/L

  20. 20

    Cove Creek Hot Spring

    id · 102°F · primitive

    270 mg/L

  21. 21

    Maple Grove Hot Springs

    id · 102°F · primitive

    260 mg/L

  22. 22

    Crane Creek Hot Springs

    id · 102°F · primitive

    250 mg/L

  23. 23

    Lakey Hot Spring

    id · 102°F · primitive

    200 mg/L

  24. 24

    Stinky Warm Spring

    id · 85°F · primitive

    190 mg/L

  25. 25

    Krigbaum Hot Springs

    id · 102°F · primitive

    180 mg/L

  26. 26

    Starkey Hot Springs

    id · 102°F · primitive

    160 mg/L

  27. 27

    Sharkey Hot Spring

    mt · 102°F · primitive

    150 mg/L

  28. 28

    Beardsley Hot Springs

    id · 102°F · primitive

    130 mg/L

  29. 29

    Little Antelope Flat Warm Spring

    id · 85°F · primitive

    130 mg/L

  30. 30

    Warm Springs

    id · 85°F · primitive

    130 mg/L

  31. 31

    Roystone Hot Springs

    id · 105°F · developed

    120 mg/L

  32. 32

    Lower Bowery Hot Spring

    id · 102°F · primitive

    120 mg/L

  33. 33

    Lava Hot Springs

    id · 130°F · developed

    110 mg/L

  34. 34

    Fairchild Hot Spring

    id · 102°F · primitive

    110 mg/L

  35. 35

    Sunflower Flat Hot Spring

    id · 102°F · primitive

    110 mg/L

  36. 36

    Pleasantview Warm Springs

    id · 85°F · primitive

    110 mg/L

  37. 37

    Owen Cabin Hot Spring

    id · 102°F · primitive

    108 mg/L

  38. 38

    Boiling River

    wy · 199°F · primitive

    100 mg/L

  39. 39

    Grape Creek Warm Spring

    id · 85°F · primitive

    91 mg/L

  40. 40

    West Pass Hot Spring

    id · 102°F · primitive

    83 mg/L

  41. 41

    Slate Creek Hot Spring

    id · 102°F · primitive

    81 mg/L

  42. 42

    Kwiskwis Hot Spring

    id · 102°F · primitive

    80 mg/L

  43. 43

    Guyer Hot Springs

    id · 102°F · primitive

    76 mg/L

  44. 44

    Ennis Hot Springs

    mt · 193°F · resort

    69.30 mg/L

  45. 45

    BLM Well (Frazier Hot Spring)

    id · 105°F · primitive

    69 mg/L

  46. 46

    Boulder Hot Springs

    mt · 102°F · resort

    67 mg/L

  47. 47

    Indian Creek Hot Spring

    id · 102°F · primitive

    66 mg/L

  48. 48

    Middle Fork Indian Creek Hot Spring

    id · 102°F · primitive

    66 mg/L

  49. 49

    Pistol Creek Hot Springs

    id · 102°F · primitive

    63 mg/L

  50. 50

    Thomas Creek Ranch Hot Spring

    id · 102°F · primitive

    63 mg/L

Sources

← All minerals