Iron

The rust-colored mineral that stains the rocks.

What it is

Iron is a dissolved metal that gives some springs a rust or orange tint and a metallic taste. Iron-rich springs stain surrounding rocks orange as the iron oxidizes on contact with air.

In hot springs

Iron is usually low (under 1 mg/L), but iron-rich springs are visually striking and geologically notable.

Cited benefits and context

The EPA sets a secondary iron standard of 0.3 mg/L for drinking water, based on taste and staining (EPA Secondary Drinking Water Standards).

There is no clinical evidence that dermal iron absorption during a soak meaningfully affects iron status. Dietary iron is well established as essential, but soaking in iron-rich water is not a treatment for iron deficiency. Iron-rich springs are notable for their color and geology, not for health effects.

Cautions

Iron-rich water stains towels, swimsuits, and skin. It is not a health intervention.

Springs ranked by most iron

48 springs with verified iron data · source: USGS Water Quality Portal

  1. 1

    The Landusky Plunge

    mt · 77°F · primitive

    12 mg/L

  2. 2

    Warm Springs Creek Hot Springs

    id · 102°F · primitive

    4 mg/L

  3. 3

    Boiling River

    wy · 199°F · primitive

    1.35 mg/L

  4. 4

    Rock Creek Hot Springs

    mt · 112°F · primitive

    0.49 mg/L

  5. 5

    Boulder Hot Springs

    mt · 102°F · resort

    0.45 mg/L

  6. 6

    Pleasantview Warm Springs

    id · 85°F · primitive

    0.32 mg/L

  7. 7

    Grand Prismatic Spring

    wy · 160°F · developed

    0.28 mg/L

  8. 8

    Malad Warm Spring

    id · 90°F · primitive

    0.27 mg/L

  9. 9

    Slate Creek Hot Spring

    id · 102°F · primitive

    0.27 mg/L

  10. 10

    Twin Bridges Hot Springs

    mt · 116°F · developed

    0.25 mg/L

  11. 11

    Cleveland Hot Springs

    id · 102°F · primitive

    0.24 mg/L

  12. 12

    Secret Valley Hot Springs

    wy · 140°F · primitive

    0.19 mg/L

  13. 13

    Goldbug Hot Springs

    id · 136°F · primitive

    0.13 mg/L

  14. 14

    Robinson Bar Hot Springs

    id · 102°F · primitive

    0.08 mg/L

  15. 15

    Warm Springs

    id · 85°F · primitive

    0.08 mg/L

  16. 16

    Lava Hot Springs

    id · 130°F · developed

    0.07 mg/L

  17. 17

    Pray Hot Springs

    mt · 120°F · developed

    0.05 mg/L

  18. 18

    Red River Hot Springs

    id · 102°F · primitive

    0.05 mg/L

  19. 19

    Sullivan Hot Springs

    id · 102°F · primitive

    0.05 mg/L

  20. 20

    Mammoth Hot Springs

    wy · 162°F · developed

    0.04 mg/L

  21. 21

    Downata Hot Springs

    id · 102°F · developed

    0.04 mg/L

  22. 22

    Ashton Warm Spring

    id · 85°F · primitive

    0.04 mg/L

  23. 23

    Chico Hot Springs

    mt · 114°F · developed

    0.03 mg/L

  24. 24

    Ninemeyer Hot Springs

    id · 102°F · primitive

    0.03 mg/L

  25. 25

    Paradise Hot Springs

    id · 102°F · primitive

    0.03 mg/L

  26. 26

    Silver Creek Hot Spring

    id · 102°F · primitive

    0.03 mg/L

  27. 27

    Mormon Bend Hot Spring

    id · 102°F · primitive

    0.03 mg/L

  28. 28

    Ninemeier Hot Springs

    id · 105°F · primitive

    0.03 mg/L

  29. 29

    Hot Springs (Hailey)

    id · 105°F · primitive

    0.03 mg/L

  30. 30

    Alhambra Hot Springs

    mt · 100°F · resort

    0.03 mg/L

  31. 31

    Medicine Hot Springs

    mt · 110°F · developed

    0.02 mg/L

  32. 32

    Firehole Lake

    wy · 160°F · developed

    0.02 mg/L

  33. 33

    Black Sand Basin Hot Springs

    wy · 165°F · developed

    0.02 mg/L

  34. 34

    Sunbeam Hot Springs

    id · 102°F · primitive

    0.02 mg/L

  35. 35

    Twin Springs

    id · 102°F · primitive

    0.02 mg/L

  36. 36

    Cox Hot Springs

    id · 102°F · primitive

    0.02 mg/L

  37. 37

    Burgdorf Hot Springs

    id · 102°F · primitive

    0.02 mg/L

  38. 38

    Sweet Warm Spring

    id · 90°F · primitive

    0.01 mg/L

  39. 39

    Cottonwood Hot Springs

    id · 100°F · developed

    0.01 mg/L

  40. 40

    Prices Warm Spring

    id · 85°F · primitive

    0.01 mg/L

  41. 41

    Broadwater Hot Springs

    mt · 151°F · resort

    0.01 mg/L

  42. 42

    Elkhorn Hot Springs

    mt · 100°F · resort

    0.01 mg/L

  43. 43

    Yellowstone Hot Springs

    mt · 104°F · resort

    0.01 mg/L

  44. 44

    Bald Mountain Hot Springs

    id · 115°F · primitive

    0.01 mg/L

  45. 45

    Lake Walcott Hot Spring

    id · 102°F · primitive

    0.01 mg/L

  46. 46

    Hospital Hot Spring

    id · 102°F · primitive

    0 mg/L

  47. 47

    Leggit Creek Hot Spring

    id · 102°F · primitive

    0 mg/L

  48. 48

    BLM Well (Frazier Hot Spring)

    id · 105°F · primitive

    0 mg/L

Sources

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