A view of the Animas River taken just after the Giold King Mine waste spill in August, via YouTube user Hayden.

A mine safety team working for the Environmental Protection Agency has inadvertently triggered the spill of a million gallons of mine wastewater in San Juan County.

The orange-colored discharge started flowing from the Gold King Mine near Silverton into Cement Creek and then the Animas River on Wednesday and prompted heath officials Thursday to warn agricultural and recreational water users to avoid the river. 

EPA confirmed Friday the discharge from the mine contained heavy metals and metalloids including lead and arsenic, along with cadmium, aluminum, copper and calcium, but the agency didn't immediately discuss amounts or health risks.

From Durango, the Animas flows south to New Mexico, through Aztec and then joins the San Juan River at Farmington. The San Juan eventually drains into the Colorado River at Lake Powell, Arizona.

Officials in New Mexico are angry the U.S. Environmental Protection Agency did not informing them soon enough about the pollution floating downstream.

New Mexico's environment secretary, Ryan Flynn, said Friday that the EPA downplayed the danger the contamination posed to wildlife, saying that potential harm can't be known until the contents of the wastewater and their concentrations are known.

The San Juan Health Department says the acidic mine water associated with the release contains high levels of sediment and metals. ​Durango has shut down water intakes until the contaminated water has passed, but the city says tap water is safe to drink.

On Friday aternoon, EPA released more details about how it says the pollution was released:

On August 5, 2015, EPA was conducting an investigation of the Gold King Mine.  The intent of the investigation was to assess the on-going water releases from the mine and to treat mine water and to assess the feasibility of further mine remediation.  The plan was to excavate the loose material that had collapsed into the cave entry back to the timbering.   During the excavation, the loose material gave way, opening the adit (mine tunnel) and spilling the water stored behind the collapsed material into Cement Creek, a tributary of the Animas River.

La Plata County Emergency Management says the plume reached the outskirts of Durango at about 7:30 p.m. County Sheriff Sean Smith says that the river has been closed to tubers, rafters and kayakers in the county and won't reopen until the river is deemed safe.

“This decision was made in the interest of public health after consultation with the Environmental Protection Agency, the Colorado Department of Public Health and Environment, San Juan Basin Health Department and representatives of the Southern Ute Indian Tribe,” Smith said. “EPA test results of the Animas River are expected within 24-48 hours, and the order will be re-evaluated at that time.”

The Durango Herald reports that Colorado Parks and Wildlife has placed four cages of fish along the river to see how the pollution affects them.

EPA told the Herald that on Cement Creek and upper parts of the Animas there were already "long-standing water-quality impairment issues associated with heavy metals," and the fish population was already "impaired." 

Larry Wolk, director of the state's health department, told CPR's Grace Hood that, "For better or worse this particular stream and river have had contaminant issues in the the past and users of the water have been aware of those contaminant issues. A spill of this type is not necessarily changing that unfortunate prior status of this stream and river--especially as it relates to aquatic life and uses for that water."

This image from the La Plata Office of Emergency Management shows Animas River mine waste pollution on Thursday, Aug. 6, 2015.

“This toxic spill into the Animas is a disturbing incident that just underscores how vulnerable our rivers, streams and fisheries are to abandoned hardrock mine pollution," said Steve Kandell of the nonprofit conservation group, Trout Unlimited. "We will be monitoring the situation in coming days to assess the impact to our waters and world-class trout fishery in the Animas River. Needless to say, the health of our community and recreation-based economy depends heavily on water quality."

Here's how the spill has been playing out on Twitter:

Editor's note: An earlier version of this story referred to arsenic as a heavy metal. Arsenic is a metalloid. The error has been corrected.