A massive wastewater spill from an abandoned Colorado gold mine sent nearly 540 tons of metals, mostly iron and aluminum, into the Animas River in 2015, according to a new report released Friday by the Environmental Protection Agency.

Although the total amount of metals entering the river system was comparable to a day or two of spring runoff, the concentration of those metals was far higher at the peak of the spill, the report said.

Last February, an EPA report estimated the total amount of spilled metals at 440 tons, but additional data and improved analysis led to the higher estimate, the agency added.

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The EPA said its research supports earlier statements that water quality in the affected river system has returned to pre-spill levels.

An EPA-led contractor inadvertently triggered the 3-million-gallon spill while doing preliminary cleanup work at the old Gold King Mine near Silverton, Colorado. The blowout affected rivers in Colorado, New Mexico and Utah.

The EPA said in its report that only 1 percent of the metals came from inside the mine, while 99 percent were "scoured" from waste piles on nearby hills and stream beds. The iron and aluminum reacted with the river water to cause the eye-catching mustard color that was visible for days as the plume traveled down the river system into Lake Powell, the EPA said.

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Besides iron and aluminum, the spill released manganese, lead, copper, arsenic, zinc, cadmium and a small amount of mercury into the river, the EPA said.

The EPA said last month it will pay $4.5 million to state, local and tribal governments for their emergency responses, but the agency rejected $20.4 million in other requests for past and future expenses.

New Mexico Environment Secretary Butch Tongate accused the EPA of using the taxpayer-funded report to try to defend its actions. The state has sued the agency over the spill.

In Utah, state government spokeswoman Erica Brown Gaddis said the report shows the metals have moved into Lake Powell, a vast reservoir in her state, highlighting the need for broader research on the effects of wastewater draining from other inactive Colorado mines into the region's rivers.

Colorado officials said they had no comment on the report.

MORE ON WEATHER.COM: Colorado Mine Spill

People kayak in the Animas River near Durango, Colo., Thursday, Aug. 6, 2015, in water colored from a mine waste spill. The U.S. Environmental Protection Agency said that a cleanup team was working with heavy equipment Wednesday to secure an entrance to the Gold King Mine. Workers instead released an estimated 1 million gallons of mine waste into Cement Creek, which flows into the Animas River. (Jerry McBride/The Durango Herald via AP)

At a Glance

A new EPA report says a 2015 spill from an abandoned Colorado gold mine leaked 540 tons of metals into the Animas River.The metals leaked during the spill were mostly iron and aluminum.The EPA also said all water in the river system has returned to pre-spill quality levels.