Significant Thermal Features

crowd of people at old faithful geyser
Old Faithful geyser, Yellowstone National Park, Wyoming.

NPS photo.

The Geothermal Steam Act

In the Geothermal Steam Act (30 U.S.C. §§ 1001-1028), Congress directed the NPS to maintain a list of significant thermal features within park units. Since 1987, sixteen Park Units have been listed as having "significant thermal features" in accordance with the Geothermal Steam Act. Significance criteria include factors such as:

  • Size and extent

  • Uniqueness

  • Scientific and geologic value

  • The extent to which the feature remains in a natural, undisturbed condition

  • Significance of the feature to the authorized purposes for which the unit was created

List of Significant Thermal Features in Parks

Aniakchak National Monument and Preserve, Alaska

  • Feature: Aniakchak Caldera (volcanic feature)

Bering Land Bridge National Preserve, Alaska

  • Feature: Serpentine Hot Springs (hydrothermal feature)

Big Bend National Park, Texas (including that portion of the Rio Grande National Wild and Scenic River located in the Park)

  • Feature: Spring No. 1 (hydrothermal feature)

  • Feature: Spring No. 4 (hydrothermal feature)

  • Feature: Hot Springs (hydrothermal feature)

Crater Lake National Park, Oregon

  • Feature: hydrothermal features at bottom of the lake (hydrothermal feature)

Gates of the Arctic National Park and Preserve, Alaska

  • Feature: Reed River Hot Springs (hydrothermal feature)

Haleakala National Park, Hawaii

  • Feature: Haleakala Crater (volcanic feature)

Hawaii Volcanoes National Park, Hawaii

  • Feature: Steaming Bluff and Sulpher Banks (hydrothermal feature)

  • Feature: Kilauea Caldera and Halemaumau Crater (volcanic feature)

  • Feature: Kilauea Iki Crater (volcanic feature)

  • Feature: Great Crack and Southwest Rift (volcanic feature)

  • Feature: East Rift Zone (volcanic feature)

  • Feature: Chain of Craters (volcanic feature)

  • Feature: Mauna Ulu (volcanic feature)

  • Feature: Puu Oo (volcanic feature)

  • Feature: Mokuaweoweo Caldera and Northeast Rift Zone of Mauna Loa (volcanic feature)

Hot Springs National Park, Arkansas

  • Feature: Hot Springs (hydrothermal feature)

John D. Rockefeller, Jr. Memorial Parkway, Wyoming

  • Feature: Huckleberry Hotsprings (hydrothermal feature)

Katmai National Park and Preserve, Alaska

  • Feature: Novarupta and vicinity (volcanic feature)

Lake Clark National Park and Preserve, Alaska

  • Feature: Redoubt Volcano (volcanic feature)
  • Feature: Iliamna Volcano (volcanic feature)

Lake Mead National Recreational Area, Arizona and Nevada

  • Feature: Black Canyon Hotsprings (hydrothermal feature)
  • Feature: Blue Point Spring (hydrothermal feature)
  • Feature: Rogers Spring (hydrothermal feature)

Lassen Volcanic National Park, California

  • Features: Lassen hydrothermal system (hydrothermal feature), including Bumpass Hell, Little Hot Springs Valley, Sulpher Works, Devils Kitchen, Boiling Springs Lake, Drakesbad Hot Springs, and Terminal Geyser

Mount Rainier National Park, Washington

  • Features: Mount Rainier (volcanic feature)
  • Features: Fumaroles at the summit of Mount Rainier and associated Ice Caves (hydrothermal feature)
  • Features: Ohanapecosh Springs (hydrothermal feature)

Wrangell-St. Elias National Park and Preserve, Alaska

  • Feature: Wrangell Volcanoes (volcanic feature)

Yellowstone National Park, Wyoming, Idaho, and Montana

  • Features: Yellowstone National Park (hydrothermal feature), including Old Faithful and approximately 10,000 geysers and hot springs

Last updated: March 10, 2020