Alarm bells went off throughout the Animas and San Juan River drainages this weekend when big storms and the historically huge avalanche cycle caused the Gold King water treatment plant to shut down temporarily. The New Mexico Environment Department went so far as to advise communities who draw from the affected waters to shut off intake points for drinking water.
Yes, the shutdown will result in untreated acid mine drainage entering the river system (about 264 gallons per minute). Yes, that will degrade water quality downstream. But, no, it is not cause for undue alarm. In fact, the worst that can happen is that water quality downstream will revert back to what it was during the decade prior to the Gold King Mine spill. Here’s a small timeline of water treatment to help explain.
1980s to 1996: Sunnyside Gold water treatment plant at Gladstone treats approximately 1,500 to 2,200 gallons per minute of acid mine drainage from the American Tunnel. Some 300 pounds of zinc, plus a host of other metals, is removed from the water each day before being released into Cement Creek. During this time nearby mine portals — the Red & Bonita, the Gold King, and the Mogul — are all dry or nearly so, meaning there is virtually no acid mine drainage.
1996: Bulkhead #1 installed about one mile into the American Tunnel at the Sunnyside Mine property line. This holds back about half of the water that was draining from the American Tunnel portal, backing it up into the 150 miles of workings of the Sunnyside Mine to become what’s known as the mine pool. The mining company continues to treat the water still draining from the first mile of the American Tunnel.
1999-2000: The owner of the Gold King Mine discovers that it is no longer dry and reports flows of 30 to 40 gallons per minute of water. Meanwhile, the owner of the Mogul Mine also notices increased flows of acid mine drainage.
2001, 2003: Bulkheads #2 and #3 installed in the final mile of the American Tunnel, to stop the remaining flows of acid mine drainage. (In fact, the tunnel continues to drain about 120 gallons per minute). Water treatment — including of the waters now flowing from Gold King and Mogul mines — continues.

2003: Kinross, owner of the Sunnyside Mine, hands off water treatment plant to Steve Fearn, then-owner of Gold King Mine.
2003-2004: Flows increase from Gold King, Mogul, and Red & Bonita, to as high as 250 gallons per minute for each mine, in addition to continued flows from the American Tunnel. Water treatment of all the discharges continued.
2004: Due to financial and legal difficulties, water treatment is shut down. Suddenly, all of that acid mine drainage (approx. 800,000 gallons per day) from four different mines is going untreated into Cement Creek, significantly degrading water quality in the Animas River, and having a deleterious effect on fish from Silverton down to Bakers Bridge.
August 2015: Gold King Mine blows out, releasing 3 million gallons of acidic, metal-loaded water into Animas River drainage.
October 2015: Gladstone water treatment plant begins treating water from Gold King mine, but not the other three draining mines. Over the next three years, the plant will occasionally treat the other mines, but not always. In other words, the water entering Cement Creek from Gladstone area mines is dirtier than it was prior to 2004.
March 2019: Treatment plant shut down temporarily due to weather and power outage.
It’s rather complicated. But the simple take is this: The water dumping into Cement Creek from Gladstone area mines was clean. In 2004 it became very, very dirty. In 2015, treatment began on just one out of four of the draining mines. And in 2019 that treatment stopped, probably only for a few days.
Bad? Yes. Catastrophe? Probably not. The catastrophe is in the collective drainage from so many zombie mines throughout the West, for which there is no simple fix.
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Jonathan P. Thompson is a contributing editor at High Country News and the author of Colorado Book Award finalist River of Lost Souls: The Science, Politics, and Greed Behind the Gold King Mine Disaster. Get a copy of River of Lost Souls.
“(Thompson) combines science, law, metallurgy, water pollution, bar fights and the occasional murder into one of the best books written about the Southwest in years.”
— Andrew Gulliford, historian and writer, in The Gulch magazine.