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Albuquerque, N.M. • New Mexico plans to sue the federal government and the owners of two Colorado mines that were the source of a massive spill last year that contaminated rivers in Utah and other western states, officials said Thursday.

The New Mexico Environment Department said it filed a notice of its intention to sue the U.S. Environmental Protection Agency over the spill. The lawsuit would be a first and also would target the state of Colorado and the owners of the Gold King and Sunnyside mines.

Utah leaders have also reserved the possibility of legal action against the EPA. In a statement issued last fall, Gov. Gary Herbert said the state "will continue to hold the EPA accountable for this mistake, including compensation for the costs we incurred in protecting Utahns from the release."

But Walt Baker, director of the Utah Division of Water Quality, said he feels confident that the EPA will follow through on its commitments to voluntarily reimburse the costs associated with Utah's response to the spill, including those the state incurred while independently monitoring affected portions of the San Juan River and Lake Powell — a monitoring program that ceased in late October after the EPA finalized a long-term monitoring plan that included the state's additional sites.

However, there are still other costs associated with spills effects in Utah, including profits lost by businesses that could not operate during the incident and damage to the river's intrinsic value caused by the August spill.

An EPA cleanup crew at the inactive Gold King Mine near Silverton, Colo., accidentally unleashed millions of gallons of contaminated wastewater Aug. 5. The spill sent a yellow plume through the Animas Valley and into New Mexico and the San Juan River, forcing farmers and municipalities to shut off their taps. It fouled rivers in Colorado, Utah and New Mexico with contaminants including arsenic and lead, temporarily shutting down drinking-water supplies and raising concerns about long-term effects to agriculture, before ultimately coming to rest in Lake Powell.

Farmers and ranchers on the Navajo Nation were left without a key water source for their crops and livestock for weeks.

The New Mexico regulators said they will sue if the EPA does not begin to take meaningful measures to clean up the affected areas and agree to a long-term plan that will research and monitor the effects of the spill.

"From the very beginning, the EPA failed to hold itself accountable in the same way that it would a private business," said Ryan Flynn, state Environment Department cabinet secretary.

A spokeswoman for the EPA did not immediately return an email from The Associated Press. Representatives from the corporations that own the mines also did not immediately respond to an email requests seeking comment.

The lawsuit is believed to be the first formal intention to sue the EPA over the spill, which many defined as an environmental disaster. It even drew the attention of activist Erin Brockovich, made famous by a movie starring Julia Roberts.

The spill occurred when workers for the agency and its contractor, Environmental Restoration LLC, started excavation work that was intended to allow them to safely drain the mine.

The accident prompted harsh criticism of the EPA for failing to take adequate precautions despite warnings that a blowout could occur. But Interior Secretary Sally Jewell said a review by her agency showed the spill was "clearly unintentional."

People who live near the idled and leaking Gold King Mine say local authorities and mining companies have spent decades spurning federal help to clean up the site.

The owners of the two mines have been disputing the source of the wastewater buildup for years. Colorado-based San Juan Corp., which owns the Gold King Mine, claims it stems from a project in the 1990s to plug a segment of the Sunnyside Mine. They say the plug caused the wastewater to build up and get pushed into surrounding mines, including Gold King.

Canada's Kinross Corp., which owns Sunnyside, disputes those claims.

In 2011, Kinross offered $6.5 million to help clean mining waste from the upper Animas River, while vowing to "vigorously contest" any effort to make Sunnyside liable for Superfund-related cleanup costs.

The mine has yet to spend the money but supports a "collaborative approach" among various parties, Sunnyside reclamation director Kevin Roach said.

— Tribune reporter Emma Penrod contributed to this article.