The Questa Mine in the Carson National Forest in northern New Mexico has produced molybdenum—used to strengthen steel for industrial uses—since 1919 when opened by R&S Molybdenum Company of Denver. Molybdenum Corporation of America was its successor in interest and Chevron Mining, Inc. acquired the mine in 2005. From 1919 to 1958, the ore was developed by conventional underground mining, but was closed until demand for molybdenum increased. Then Congress authorized and the United States contracted with Molycorp to conduct exploration, drilling, and sampling to determine if further production at the Questa Mine was feasible; thereafter, from 1964 to 1983, Molycorp engaged in open-pit mining at the Questa Mine, from which the vast majority of the waste rock at issue was generated. In 1983, underground mining resumed and continued until 2014.
When the United States contracted with Molycorp, Molycorp had located 2,226 acres of lode claims near existing operations and was using those lands for waste rock disposal. At the request of the United States, Molycorp agreed to relinquish its claims and engage in a land exchange with the United States. By that time, Molycorp had already disposed of 80 percent of the waste rock ultimately dumped on the selected lands.
In 2000, New Mexico requested that the Environmental Protection Agency list the mine as a Superfund site under CERCLA. In 2010, the EPA’s decision doing so found that the cost of remediation could reach $1 billion.
In September of 2015, a New Mexico federal district court held that the United States was not liable under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), even though the government held title to the lands and exercised oversight over them when the mine waste disposal occurred.
On January 26, 2016, the American Exploration & Mining Association and the Colorado Mining Association, two century old mining associations, filed an amici curiae brief with the U.S. Court of Appeals for the Tenth Circuit in Denver, urging the court to overturn the lower court’s ruling that the United States does not share liability for a “Superfund” site on its land. On November 14, 2016, oral argument was held before the three-judge panel. On July 19, 2017, consistent with the brief filed by MSLF on behalf of its clients the AEMA and the Colorado Mining Association, the Tenth Circuit reversed the ruling of the New Mexico federal district court and held that the United States, as a landowner, is an “owner” and a potentially responsible party (PRP) and thus “strictly liable for its equitable portion of the costs necessary to remediate the contamination arising from mining activity on federal land.”