Homestake will have to carry out extensive radiation surveys at the mines, to assess risks, backfill open holes and alleviate surface features that pose physical threats, the EPA said.
EPA’s Pacific Southwest Region administrator Jared Blumenfeld said: "EPA has a polluter pays policy that seeks to make those responsible for environmental damage pay for the cleanup.
"This work, which will cost about $500,000, is another element in our partnership to deal with the toxic legacy of abandoned uranium mines."
Cleaning up the uranium contamination at the four mine sites is part of a program to screen, assess, and clean up abandoned uranium mines across Navajo Nation.
Homestake Mining’s work is expected to be completed by fall 2015. From 1977 to 1982, the Mariano Lake mine operated as uranium mine.
Around four million tons of uranium ore was extracted from mines in Navajo Nation between 1944 and 1986.
