Molycorp operates a molybdenum mine approximately 4 miles East of Questa, New Mexico, a mill approximately 6 miles East of Questa, and tailings impoundment site in Questa. It is currently regulated by the New Mexico Environment Department (NMED), including the Ground Water Quality Bureau, Surface Water Quality Bureau; the Mining and Minerals Division of the New Mexico State Energy, Minerals and Natural Resources Department; and the Environmental Protection Agency (EPA). On April 1, 2000, Governor Gary Johnson wrote a letter to the EPA requesting that Molycorp be put on the National Priorities List (NPL) (Superfund). Molycorp is a wholly-owned subsidiary of Unocal Corporation, one of the world's largest oil companies.