This story was updated on August 11 to reflect a change in development.
The Environmental Protection Agency (EPA) accidentally released 3 million gallons of contamination into the Animas River, 55 miles north of Durango, Colorado, the Denver Post reported Thursday. La Plata County closed off the river to the public for more than 70 miles, from San Juan County to New Mexico.
The wastewater came from Gold King Mine, located north of Silverton, where the EPA was testing for pollutants. Heavy metals, including iron and copper, poured into the river, turning it bright orange.
"The river looks pretty nasty," Deputy Stephen Lowrance of the San Juan County Sheriff's Office told the Denver Post. "It doesn't look like water, it just looks like sludge."
The EPA is working to test the contaminated water. It expects to receive results on Friday.
UPDATE: AUGUST 11, 9:30 MDT: A previous version of this article stated that 1 million gallons of contaminated water had been spilled, but the amount was actually closer to 3 million, according to the Denver Post.