Mountain Home Air Force Base

Mountain Home Air Force Base is a United States Air Force installation in southwestern Idaho, located roughly 12 miles southwest of the city of Mountain Home and about 40 miles southeast of Boise. The field officially opened on August 7, 1943, and was first used to train aircrews during World War II. Since 1972, the host unit has been the 366th Fighter Wing, nicknamed the Gunfighters, which today operates F-15E Strike Eagles and supports worldwide contingency operations. The base covers roughly 9 square miles of high desert terrain. Decades of aircraft maintenance, industrial operations, and waste disposal have left a record of environmental concerns that remain under active investigation and cleanup.

Like many long-operating military airfields, Mountain Home has been associated with the release of several chemicals into its soil and groundwater. Past practices included disposal of wastes in on-base landfills and sanitary sewers, and the use of waste oil in fire-training exercises, which contaminated soil and groundwater. The contaminants identified below have raised concerns about potential exposure for service members, their families, and civilian workers who lived or worked at the installation.

1. Solvents and volatile organic compounds: Industrial degreasing and aircraft maintenance generated chlorinated solvents, including compounds such as TCE, which were detected in groundwater at the base. Long-term exposure to certain solvents has been associated in some studies with kidney, liver, and other health concerns.
2. Jet fuel: Refueling operations, spills, and fire-training activities introduced petroleum hydrocarbons and waste oils into the soil and groundwater. Exposure to fuel-related compounds has been associated with a range of potential health effects depending on dose and duration.
3. AFFF (aqueous film-forming foam): The Air Force used AFFF firefighting foam at Mountain Home to extinguish fuel fires and during fire-training drills. This foam is the primary source of the PFAS compounds described below, and concerns about potential exposure have prompted ongoing study.
4. PFAS: The broader family of per- and polyfluoroalkyl substances known as PFAS entered groundwater through decades of AFFF use. These chemicals are persistent in the environment, and research has examined possible links to several health outcomes, leaving open questions about long-term exposure.
5. PFOS: On-base testing detected PFOS at concentrations reported as high as 230 parts per trillion. PFOS has been associated in some studies with effects on the immune system, cholesterol, and other measures, though research continues.
6. PFOA: Sampling also found PFOA at levels reported as high as 210 parts per trillion on base. PFOA has likewise been the subject of health research, and concerns about potential exposure have contributed to the ongoing remedial investigation.

Mountain Home Air Force Base was placed on the EPA National Priorities List, the Superfund program for the nation's most contaminated sites, in August 1990. A Federal Facility Agreement among the Air Force, EPA Region 10, and the State of Idaho was signed in 1992, organizing the work into operable units. Remedies have included capped landfills, soil vapor extraction systems, institutional controls, and long-term groundwater monitoring, while a separate PFAS remedial investigation remains underway. A Snake River water project intended to protect the long-term drinking water supply is scheduled to be completed in 2026.

Veterans, family members, and others who spent time at Mountain Home Air Force Base may wish to stay informed as monitoring and cleanup continue. Those with questions about possible exposure are encouraged to speak with the U.S. Department of Veterans Affairs about screening, benefits, and current guidance, and to keep records of where and when they served.