Press "Enter" to skip to content

The clog near the top of the Arkansas

Brief by Central Staff

Mining – March 2008 – Colorado Central Magazine

Does a major environmental disaster loom for the Arkansas River above Pueblo? There was sure a lot of talk about it as we went to press.

The fear is that high water, thanks to a heavy snowpack, will force its way past an obstruction in the Leadville Mine Drainage Tunnel, surge past the treatment plant, and roar down the Arkansas River, carrying a heavy load of minerals and other pollutants that kill aquatic life, from tiny bugs to brown trout.

Leadville’s historic mines sit on the hillsides east of town, and ever since they first started digging shafts in about 1875, those holes have collected water. At first, the mines were pumped dry, but that’s expensive.

In 1906, the four-mile Yak Tunnel was completed. It ran under many mines, thereby draining them into California Gulch, a tributary of the Arkansas River. It was also used for haulage; instead of lifting the ore, the mines could put gravity to work.

Mine drainage, as you might suspect, is not the cleanest water around. The water becomes acidic when it accumulates against sulfide rocks, and many ores are sulfides. Once turned acidic, the water dissolves and carries minerals like zinc and cadmium, and in sufficient concentrations, these are toxic to river life.

No one worried much about that in 1906, and it wasn’t a concern in 1943, either, when work began on the Leadville Mine Drainage Tunnel. World War II was raging, the United States needed lead and zinc, and to get full production from mines not drained by the Yak, the U.S. Bureau of Mines started work on a new drainage tunnel.

The war ended in 1945, and so did work on the tunnel. But the Korean Conflict came in 1950, and work resumed. The 12,000-foot tunnel was completed in 1952.

As mining historian Stephen M. Voynick explains in Leadville: A Miner’s Epic, “Technically, the tunnel was a success, draining 4,000 gallons of water per minute. Practically, however, it was a failure, draining only abandoned, collapsed mines and dumping the water, acidic and high in dissolved mineral content, into the Arkansas River.”

In 1959, as part of the Fry-Ark Project, the tunnel was transferred from the Bureau of Mines to the Bureau of Reclamation. After federal environmental laws came into effect in the early 1970s, the Environmental Protection Agency ordered the Bureau of Reclamation to clean up this discharge — it and the Yak were responsible for 90 percent of the pollution in the Arkansas.

So a $5 million treatment plant went on line in 1992, handling about 1,500 gallons per minute, and the river ran much cleaner, since the Yak treatment plant also began running that year.

But sometime since then — nobody seems to know exactly when — the tunnel collapsed somewhere, which blocked most of its usual flow. The water began backing up in the old mines. The longer the water stays there, the more toxic it gets. The growing weight of the water could lead to a “blow-out” past the blockage, which would also demolish the treatment plant and send a surge downstream, endangering residents and polluting the river.

Even without a blow-out, however, higher water underground means more seepage of toxic water, which has already been reported.

One estimate has it that one billion gallons of water are backed up. That’s about 3,100 acre-feet. According to the U.S. Geological Survey, the Arkansas River’s flow averages about 15 cubic feet per second near Leadville in the winter, which works out to 30 acre-feet per day. In other words, there could be 100 days of winter flow, all of it toxic and ready to dump.

On February 14, Lake County Commissioners, joined by State Sen. Tom Wiens (he’s from Castle Rock but the district stretches to Lake county), asked for an official disaster declaration by state and federal governments, so that money will be available for pumping or tunnel work to get the water treated and released in an orderly way.

Then, Governor Ritter weighed in, and now local, state, and federal authorities are looking for answers. But the federal government should have been on top of this long ago. We note that Leadville mining has an up-and-down relationship with the feds. When it’s war-time and minerals are needed, the feds want maximum production, no matter what the environmental cost. But once the shooting stops, the feds are in no hurry to help clean up the mess.