tors engage with the park in a manner that promotes preserva- tion. However, damage to Yellowstone’s thermal features at any scale must be addressed and prevented because the damage is often irreversible. The effects of vandalism have been allevi- ated to some degree by aggressive public education campaigns that include roving interpretive rangers, signs, and informa- tion published in the park newspaper about how vandalism damages thermal features (Taylor 2005). Additionally, dedi- cated volunteers such as Ralph Taylor, president of the Geyser Observation and Study Association, perform surface cleaning of thermal features during the heavy summer tourist season as well as monitor geyser activity.
Potential Impacts from Geothermal Energy Development
While vandalism and in-park developments have altered individual features within Yellowstone, potential impacts from external threats may pose the greatest risk to the park’s hydrothermal systems. Two known geothermal resource areas (KGRAs), Island Park and Corwin Springs, are located adja- cent to park boundaries (Figure 4). The potential for geother- mal development in these areas poses a risk because the hydro- logic connections between the KGRA and park features are poorly understood (U.S. Forest Service and Bureau of Land Management 1979, Sorey 1991). After the Geothermal Steam Act of 1970 opened federally-owned portions of the KRGAs to geothermal leasing, more than 200 applications were filed for locations in Island Park, but none were approved because of concerns about the effect on the park of extracting subsur- face fluids there. Amendments to the Geothermal Steam Act in 1984 banned federal geothermal development in the Island Park KRGA. However, leases for 25,000 acres of state and pri- vate land were granted, and potential geothermal development from these leases still threatens park resources (Harting and Glick 1994).
In 1986 the Church Universal and Triumphant drilled a geothermal well near Corwin Springs, only 8 km from the park boundary and 14 km from Mammoth Hot Springs, sparking an outcry by the NPS and conservation groups. The well significantly reduced the flow of LaDuke Hot Springs, located adjacent to the well site. This drilling and other con- cerns regarding resource development adjacent to national parks resulted in the Geothermal Steam Act amendments of 1988 that gave the Secretary of the Interior the right to turn down a lease application if it was “reasonably likely to result in a significant adverse effect on a significant thermal feature within a unit of the National Park System.” The amendment also specified that there would be no further development or geothermal leasing at Corwin Springs until the U.S. Geological Survey and NPS conducted a study on the hydrologic connec- tions and possible impacts of development on Yellowstone’s thermal features. The study later found that there was a pos-
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sible hydrologic connection between Mammoth Hot Springs and the Corwin Springs KGRA, but determined that limited development could continue at LaDuke Hot Springs without adversely affecting Yellowstone’s thermal features (Sorey 1991). In 1992, the moratorium on geothermal development at Cor- win Springs KGRA expired, so potential harm to Yellowstone’s thermal features could still result if large-scale development occurs. More legislation was introduced in 1994 to protect Yel- lowstone’s thermal features, particularly the Old Faithful Pro- tection Act, which would ban geothermal development within 15 miles of the park boundary, but it failed to pass in the Senate (Harting and Glick 1994).
A major milestone in the protection of Yellowstone’s thermal features was the signing of the Montana–NPS Water Compact in 1994. The compact allows Yellowstone and Gla- cier national parks and Big Hole Battlefield National Monu- ment to retain all federally reserved water rights based on the year of each park’s establishment. The compact also addresses the protection of Yellowstone’s unique hydrothermal systems. This was accomplished by designating a Controlled Ground- water Area located just north and west of the park that has potential hydrologic connections with Yellowstone’s thermal features (Amman et al. 1995, Custer et al. 1994). The compact allows restrictions on both hot and cold groundwater with- drawals and geothermal development within this area to pre- vent adverse effects to Yellowstone’s thermal features.
The NPS has only limited water rights agreements with Yellowstone’s other two bordering states of Idaho and Wyo- ming. Idaho has granted Yellowstone all reserved water rights,
Figure 4. there is currently no geothermal development at Corwin Springs or Island Park. If development occurs in the future, it could potentially threaten Yellowstone’s unique geothermal features.