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Mine pollution changed river chemistry

Early pH levels show water is as acidic as coffee

The million gallons of pollution slowly flowing down the Animas River since Wednesday has radically changed the acidity of the water over the past few days, EPA officials have found.

On Saturday, the agency released its first summary of pH levels collected from Cement Creek and the Animas River. The results showed that the polluted water dropped pH levels, making the water more acidic and more likely to dissolve metals. High levels of dissolved metals are more toxic to aquatic life, Peter Butler, a co-coordinator for the Animas River Stakeholder Group, said Saturday.

The EPA would not comment on the impact the pollution was having on fish and other wildlife.

“The evaluation of impacts of these pH levels on fish and other aquatic life is ongoing,” the release said.

The EPA officials said they hoped to release the levels of heavy metals Sunday. These levels will help the agency project the long-term consequences of the spill, said Shaun McGrath, administrator for EPA’s Region 8.

Samples were taken Thursday at a number of locations along Cement Creek and the Animas River, between Silverton and past Farmington.

Except for locations within Cement Creek, pH levels were generally measured before the arrival of the contaminant plume and found the range between 6.5 and 7.6. When the toxic water passed a sampling location below Silverton, the pH lowered to about 4.8, according to a news release issued Saturday by the EPA.

At low pH levels, iron and aluminum become particulates that reflect the light, and these particulates created the orange hue in the water, Butler said.

These particulates of iron and aluminum are less toxic to aquatic life than dissolved particles, but they can coat the bottoms of streams and river beds and smother animals, he said.

Water acidity levels in the Animas above the confluence with Cement Creek have been consistent over the past two days at about 6.4 to 6.8, the release said.

Since the mine release, the acidity level in Cement Creek has remained low at 3.74. The water in Cement Creek does not support fish populations.

The EPA offered some explanations why releasing the total metal loading in the river has taken several days in the news release.

The distance between sampling locations involves driving time, especially where locations on the river are in remote, difficult-to-access locations, the EPA said. Once at the location, collecting filtered sample takes a half hour or more.

Samples are taken from the river using a hand pump or peristaltic pump.

The standard procedure for analyzing metals requires a 16-hour hold time with the preservative. The EPA planned to modify the procedure to reduce or eliminate the hold time.

Transporting the samples to labs and the lab analysis itself has also been slowing the process.

Small labs may be able to guarantee only a 24 to 48 hour turnaround time. Medium- and large-capacity labs are able to provide much faster turnaround times, and sometimes same-day results.

“EPA is currently using a local laboratory in Durango, which has been extremely cooperative and plans to work through the weekend for this project; however, it is a small-capacity lab and will likely not be able to process the high volume of samples anticipated to be taken,” an EPA release said.

The first round of 19 samples collected the evening of the spill and morning after were immediately driven to the EPA laboratory in Golden and prepped for analysis.

The EPA is exploring options for working with another lab, which will involve driving or shipping samples for delivery.


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