On Aug. 5, about 3 million gallons of contaminated water burst out of an abandoned mine above Silverton and sent a plume of cloudy, orange water down Cement Creek to the Animas River, through the heart of Durango, and on into the San Juan River in New Mexico, the Navajo Nation and Utah. Downstream: Lake Powell.

The plume of acidic orange water, containing arsenic, lead and other toxic heavy metals, had built up as a result of “wild west” mining activity dating back to the 1870s, as well as work to plug some mines, which ultimately redirected contaminated water into others. The massive plume was set loose by workers for the U.S. Environmental Protection Agency attempting to assess and remediate the source of an ongoing trickle of pollution from the Gold King mine.

Fortunately, immediate biological impacts appear to be less dramatic than the appearance of the water suggests. Colorado Parks and Wildlife has been holding fish in cages in the Animas River to see if exposure to the plume would kill them, and so far it hasn’t. The Mountain Studies Institute reports that the small bugs that live in the stream bed and make up the base of the aquatic food chain also seem to be holding on at their sampling sites in the Durango area. The fact that the highest concentrations of contaminants passed through the area fairly quickly seems to have helped.

In terms of human health impacts, drinking water intakes on the Animas River for Durango, Farmington, New Mexico, and other communities were shut off before the plume arrived. These communities are relying on stored water and other sources for the time being.

Medium term, irrigators relying on the Animas and San Juan rivers could lose crops if they don’t get the go-ahead to open up their diversions again soon and/ or get lucky with rain. Rafting companies are certainly feeling an economic hit as people are kept off the river.

Longer-term impacts are harder to assess, since health impacts to both people and wildlife depend on the level and duration of exposure to the contaminants. It’s clear that the heavy metals will settle out into the sediments on streambeds and the bottom of Lake Powell, but it’s not clear how concentrated the contaminants will be and to what extent they will move back into the water column in response to storms and floods.

HISTORICAL PERSPECTIVE

In assessing how this catastrophe fits into the overall regional water picture, it is instructive to zoom out geographically and look back in time. The 3 million gallons of contaminated water from the spill translate to a little over 9 acre-feet of water. This quantity is dwarfed by the approximately 13 million acre-feet currently in Lake Powell, despite the fact that it is only 54 percent full. Particularly given that the heavy metals will increasingly drop into the lake floor as the water slows down, impacts to the Grand Canyon and downstream water users should be minimal.

Looking back in time, Jonathan Thompson points out in a web article for High Country News (“When our river turned orange”) that pollution of the Animas River from mines has been a problem for more than 100 years, with previous dramatic blow-outs, and waxing and waning impacts to fish as remediation efforts have gained and lost ground.

Looking ahead, this latest catastrophe may stimulate more comprehensive solutions to this longstanding problem, in the Animas Watershed and around the region.

WIDESPREAD CONCERNS

The Colorado Geological Survey inventoried abandoned and inactive mine sites on National Forest lands across Colorado between 1991 and 1999. Of the 18,000 mine features inventoried, 900 presented environmental problems significant enough for future study. About 250 of those were found to be causing significant or extreme environmental degradation. Priority watersheds were identified in the Animas, Uncompahgre, Arkansas and Rio Grande headwaters.

Fortunately for the Colorado River Valley, the inventory did not identify any mine features on the White River National Forest that were causing environmental degradation. The White River National Forest is the source of most of our drinking water. However, problematic sites do exist in the Gunnison National Forest.

Cleanups of leaking abandoned mines have been hampered by the fact that many of the companies that established and worked the mines no longer exist. Nonprofit watershed groups often take on these problems, but are hampered by a lack of resources and liability concerns – which the Gold King blow-out demonstrates are not just hypothetical.

Additional federal resources can come with Superfund designations, but communities often shy away from the stigma associated with such a designation, which had previously been proposed for the upper Animas. Communities may now reassess the dangers of the potential stigma of a Superfund designation in light of the flood of publicity that has attended the orange plume descending the Animas and San Juan rivers.

Hannah Holm is coordinator of the Water Center at Colorado Mesa University, and Dan Ben-Horin is a watershed specialist with the Middle Colorado Watershed Council. This is part of a series of articles coordinated by the CMU Water Center in cooperation with the Colorado and Gunnison Basin Roundtables to raise awareness about water needs, uses and policies. To learn more, go to http://www.coloradomesa.edu/WaterCenter.