The Arizona Department of Environmental Quality and the Arizona Attorney General's Office announced Monday that Asarco will pay $20,000 in civil penalties under a consent judgment.
The fine stems from an incident in Feb. 2007 when a pipeline straddling the Gila River and connecting to Asarco's Hayden mining operation ruptured.
ADEQ said the rupture led to the release of an estimated 1,500 gallons of tailings onto the banks and main channel of the river.
Asarco issued a news release saying the company installed a pipeline with design and engineering improvements, rather than repair or replace the leaking coupling, at a cost of approximately $1.7 million.
Asarco President and Chief Operating Officer Manuel Ramos said the mining company "takes its compliance obligations very seriously."