Church Rock uranium mill spill
1979 CE.
Shown on the map at 35.651°, -108.506°.
The Church Rock uranium mill spill occurred in the U.S. state of New Mexico on July 16, 1979, when United Nuclear Corporation's tailings disposal pond at its uranium mill in Church Rock breached its dam. The spill remains the largest release of radioactive material in U.S. history, having released more radioactivity than the Three Mile Island accident four months earlier. The Church Rock uranium mill, which operated from June 1977 to May 1982, was located on privately owned land about 17 miles (27 km) northeast of Gallup, New Mexico, bordered to the north and southwest by Navajo Nation Tribal Trust lands. The milling of uranium ore there produced an acidic slurry of ground waste rock and fluid (tailings) that was pumped to the tailings disposal area. The breach released more than 1,100 short tons (1,000 t) of solid radioactive mill waste and 94 million US gallons (360,000 m3) of acidic, radioactive tailings solution into the Puerco River through Pipeline Arroyo. An estimated 1.36 short tons (1.23 t) of uranium and 46 curies of alpha contaminants traveled 80 miles (130 km) downstream to Navajo County, Arizona, and onto the Navajo Nation.
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