Amid festering anger and fear across three states, the head of the Environmental Protection Agency headed to Colorado on Wednesday, a week after her organization uncorked a gusher of toxic waste in that state.

The accident sent more than 3 million gallons of sludge down the Animas River, which ran an unforgettable shade of highlighter yellow and hot mustard orange for more than a hundred miles. The plume triggered a state of emergency in Colorado and New Mexico, and sparked anxiety about belly-up fish and undrinkable water. Contaminated by arsenic and lead, the river itself remains closed until August 17.

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At an appearance in Washington earlier Tuesday, EPA administrator Gina McCarthy said the agency accepted responsibility for the spill and was fully mobilized to limit the damages. “It pains me to see this happening,” she admitted, “but we are working tirelessly to respond and have committed to a full review of exactly what happened to ensure it cannot happen again.”

By law, the agency has to pay people who suffer personal injury or property damage as a result of governmental actions, and there’s likely to be a number of those claims. Both the Navajo Nation, which depends on the waterways fouled by the spill, and the state of New Mexico, which has mobilized a million-dollar response, have pledged to hold the EPA accountable. Close video Communities along Animas River spill demanding answers Colorado Gov. John Hickenlooper has declared the toxic mine spill in the Animas River a disaster emergency. The EPA has shut off long stretches of the river, but now farms are suffering because there is no water to irrigate crops. President of Farmers… Colorado Gov. John Hickenlooper has declared the toxic mine spill in the Animas River a disaster emergency. The EPA has shut off long stretches of the river, but now farms are suffering because there is no water to irrigate crops. President of Farmers… share tweet email Embed

The error has already turned this spill into a political headache, too. The Wall Street Journal editorial board mocked the agency on Wednesday. “Who you gonna call today when the E-men dump three million gallons of toxic slurry down the rivers of the West?” the paper wrote. “The lesson is to leave well enough alone, and that government lives by a double standard.”

The ecological costs of the spill remained uncertain late Tuesday. The orange color had dissipated, but it left behind layers of sludge in some places and toxins still cruising downriver toward Lake Powell in Utah and the San Juan River in New Mexico.

The most worrisome pollutants are arsenic and lead, which peaked at 300 times and 3,500 times the normal levels, according to preliminary federal data. But Colorado’s Parks and Wildlife Department has found “no evidence” of adverse effects on fish and wildlife along the river corridor, the state announced on Tuesday.

Biologists put more than a hundred trout fingerlings in cages along sections of the river last week, so they could monitor the water’s effect. “A visit this afternoon found all lively little fish,” the La Plata County government said in announcing the state results. “Biologists have also walked and floated parts of the river looking for evidence of dead fish,” and found none.

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The EPA is cautiously optimistic. “Thankfully, there have been no reported cases of anyone’s health being harmed,” McCarthy said on Tuesday. “Additionally, from initial sampling results, as the plume has advanced seeing elevated levels, and as it moves on, we are seeing a downward trajectory toward pre-event conditions.”

Still, small towns hang like a charm along the river, depending on revenue from rafting, kayaking and fly fishing. All those industries have been damaged by the spill. At least seven utilities closed their intake gates, preventing contamination of drinking water, but farmers and tribal leaders aren’t sure they’ll have enough clean well water to get through the season.

The less calculable costs, of course, are all psychological. The Animas River was the backdrop for parts of the film “Butch Cassidy and The Sundance Kid,” an area renown for its beauty. “The river for us is an integral part of our community,” state Sen. Ellen Roberts, who represents Durango, told msnbc. “It’s where people get married. People do their own private ceremonies along there. It’s our daily life.”

“It makes me want to cry,” added Jay Else, a resident of Durango, the closest big town to the spill. “I don’t know if it’s ever going to be right again.”

Slowly, the EPA has started to say more about the origins of the spill. It came from inside the Gold King Mine, shuttered since 1923. The mine had been leaching into the surrounding area, including into the Animas River. In an effort to stop the toxic bleed, the EPA planned to slurp out the sludge and dispose of it properly.

Workers misjudged the pressure, however, and their movements disturbed an earthen wall that secured the liquid, releasing a waterfall of pollution downstream. It’s important that the agency address the error, experts point out, because the work is far from done. Colorado alone has dozens of similarly abandoned mines, each one a potential blow-out in waiting.