ABANDONED URANIUM MINES AND MILLS AND THEIR POTENTIAL EFFECTS ON WATER QUALITY ON TRIBAL LANDS IN THE WESTERN UNITED STATES

The water quality of surface water and groundwater on tribal lands in Arizona, Colorado, New Mexico, South Dakota, Utah, and Wyoming are currently affected or have the potential to be affected by the legacy of uranium mining and milling. For example, active or abandoned uranium mines and mills are adversely affecting or have the potential to adversely affect the water quality of surface water and groundwater on the Ute Mountain Ute Indian Reservation in southern Utah and Colorado, the Wind River Reservation in central Wyoming, and the Navajo Indian Reservation in New Mexico and Arizona. Mobilization of uranium and other trace elements from abandoned mines in the Black Hills has the potential to adversely affect surface-water quality on the Standing Rock Sioux Reservation and the Cheyenne River Sioux Indian Reservation in South Dakota. This talk presents an overview of the distribution of abandoned uranium mines and milling sites on these Indian Reservations and their potential effects on water quality. The persistence of uranium in surface water and groundwater derived from mining and milling activities and the problems associated with remediation of uranium-impacted surface and groundwater are discussed based on the results of three recently completed USGS studies. The primary objectives of these studies were to (1) evaluate the potential for offsite migration of uranium and other radionuclides in groundwater at the White Mesa Uranium Mill in Utah and (2) provide a third party interpretation of monitoring data collected by the U.S. Department of Energy (DOE) at Uranium Mill Tailings Remedial Action (UMTRA) sites on the Wind River Reservation near Riverton, Wyoming, and the Navajo Reservation near Shiprock, New Mexico.