Under an August 27, 2014, Administrative Order on Consent (AOC) Homestake Mining Company of California will assess contamination and address safety hazards at four abandoned uranium mines in the Mariano Lake and Smith Lake areas on the Navajo Nation. The U.S. Environmental Protection Agency (EPA) and Navajo Nation will oversee the work totaling about $500,000. Under the agreement, Homestake will also set aside funds for EPA’s oversight of future cleanup. Homestake Mining Company case summary.You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.