DENVER — The Environmental Protection Agency announced Friday that water quality in Colorado and New Mexico rivers has returned to normal since the massive Gold King Mine spill unleashed by an EPA-led crew.
Nearly 540 tons of metals rushed into Colorado’s Animas River in nine hours, a release that normally would have taken four to seven days or “one to two days of high spring runoff,” according to the EPA’s final analysis of the August 2015 spill.
Even so, the report said samples collected over the next year found that mineral levels are now the same at the Animas and San Juan rivers before they were contaminated by the bright yellow plume.
“The research supports EPA’s earlier statements that water quality in the affected river system returned to the levels that existed prior to the GKM release and contamination of metals from the release have moved through the river system to Lake Powell,” said the EPA statement.
At the same time, “the concentrations of some metals in the GKM plume were higher than historical mine drainage,” said the EPA.
The massive spill has represented an ongoing headache for the Obama administration since an EPA-led crew uncorked 3 million gallons of toxic wastewater while clearing debris from the inactive mine near Silverton, Colorado.
House and Senate Republicans have accused the administration of holding double-standard on the spill, arguing that anyone else responsible for the acidic drainage would have faced more severe consequences, while EPA administrator Gina McCarthy has insisted that the agency is taking full responsibility.
An Interior Department investigation found the crew failed to assess the water pressure behind the debris before excavating, but no government officials or workers have been punished or fired for their involvement, according to a probe by the House Natural Resources Committee.
The latest EPA analysis stressed the positive, saying there have been no fish kills or harm to aquatic life so far. Tests of well-water samples have fallen within federal drinking-water standards, and other water samples tested below the agency’s recreational screening levels.
On the minus side, samples taken in the first nine months found some metal concentrations exceeded at times state and tribal water quality criteria, although the report said historic mining and activity and naturally occurring levels of metals may have contributed to the higher readings.
The spring snowmelt disrupted metals from the spill that had settled in the sediment of the Animas and San Juan rivers, elevating concentration levels in water samples throughout the system.
Metals from the spill that crossed three states and two tribes included aluminum, iron, manganese, lead, copper, arsenic, zinc, cadmium and “a small amount of mercury,” the report said.
“Concentrations were low, but the duration of snowmelt strongly implies that the mass of GKM metals that had settled in the river beds was moved downstream to Lake Powell by the end of the snowmelt period,” said the EPA analysis.
The agency said the remaining contamination from the spill is expected to flow this year to Lake Powell.
“Results from this analysis will inform future federal, state and tribal decisions on water and sediment monitoring,” said the EPA statement. “EPA will continue to work with states and tribes to ensure the protection of public health and the environment in the river system affected by the Gold King Mine release.
New Mexico and the Navajo Nation have filed lawsuits against the EPA over the spill, while New Mexico has also sued Colorado for failing to do more to remediate contaminants leaking from its inactive and abandoned mines.
House Natural Resources chairman Rob Bishop said in an Aug. 5 statement marking the one-year anniversary of the spill that Interior and EPA officials have been “inconsistent and artfully misleading,” saying there has been “zero accountability.”
“EPA’s disaster dumped hundreds of tons of pollutants into a river that flows across four states — affecting farmers, treatment systems for safe drinking water and livelihoods, but no one has been punished,” Mr. Bishop said. “These communities, especially in Colorado, New Mexico and Navajo Nation, deserve better. They deserve answers.”
EPA officials have noted that the rivers have long been polluted by mining drainage, in some cases from mines dating back to the Gold Rush.