Willoughby: Water beneath the mountain
Legends & Legacies
The disastrous discharges from the Gold King Mine raise concerns throughout the mining West. Could that happen in Aspen? Although the answer is complex, it may be reassuring.
Aspen’s main mineral belt extends from Red Mountain south to the confluence of Castle and Conundrum creeks. In town, the belt is nearly a mile wide. It narrows to only a few hundred yards toward the Little Annie Basin. The ore-laden rock lies within splinters of a major longitudinal fault. The faults continue to slide sideways while blocks of material move up and down within them. These changes fracture and grind rock and allow minerals to penetrate from below. The same fracturing allows an influx of water.
The water, snowmelt from above, took part in the mineralization process. As water flowed through mineral zones it dissolved silver, lead and zinc deposits. The solution left lead closer to the surface and redeposited silver at lower elevations.
How much water? Water was the scourge of Aspen’s mines. Most deep mines had pumps that pulled water to the surface or tunnels that drained it from below. Water seeped into the Midnight Mine while workers dug a tunnel from Queens Gulch to the Little Annie Basin. They had to abandon the project for more than a year because they were standing in water above their knees. For decades, the amount of water in the tunnel fluctuated by season and tended to lag behind the snowmelt.
We know something about the nature of the underground water because the U.S. Geological Survey studied it in 1924 after the mining boom. Edson Bastin examined Aspen’s ore to determine the origins of its deposition. He also analyzed water at the 15th level of the Smuggler and in the Durant Tunnel. That tunnel contained an underground waterfall deep within Aspen Mountain.
As Bastin described the Smuggler sampling as “a voluminous stream from a watercourse in dolomite and probably draining from ground level down to between the 15th and 13th levels — at a depth of around 800 feet. It was clear and of ordinary temperature.” Water from the Durant tunnel still flows out of the mountain and feeds ditches around Glory Hole Park.
In water samples from the Smuggler, Bastin found calcium at 43 parts per million, manganese at 27 and sodium at 12. In the Durant he found a richer solution: 137 parts calcium, 59 parts magnesium and 40 parts sodium. Sulfates topped out at 481 parts per million in the Durant. Bicarbonate reached 257 parts per million in the Smuggler.
In other qualities, the waters ranged from neutral to slightly alkaline. Low content of alkalis, chlorine and metals combined with high content of earths. Bastin concluded, “It is probable that the descending mine waters that deposited most of the native silver of the Aspen ores were similar in general composition” to those he sampled.
Aspen did experience river contamination from mining, but that pollution came from the mills at the edge of the Roaring Fork, near Rio Grande Park. In the milling process, water separated nonmineral material and carried it away into the river. The river bottom was not visible from the mill location until beyond Red Butte. Aspen’s sewage dumped, untreated, into the river at about the same point as the mills. Locals avoided fishing that stretch of river until after the last mill closed in the late 1920s.
Over eons, water — arguably the most persistent mover of minerals — rearranged ore deposits. Although the result would be hailed in our lifetimes as one of the great silver deposits of the world, silver had originally concentrated in more accessible locations.
Water continues to wash through Smuggler and Aspen Mountain, as it has through geological time. Snowmelt sinks into the mineral zone. Some emerges as springs. Some follows the path of old caved tunnels. Most passes into the Roaring Fork groundwater supply. It flows over impermeable rock layers in the glacial material that covers the valley floor.
In the preventable blowout at the Gold King mine, Environmental Protection Agency workers triggered the release of 3 million gallons of wastewater. The toxic brew of heavy metals, previously pent up behind a bulkhead, dumped into the Animas River and whisked downstream to New Mexico. Aspen’s clear, flowing water — free of bright colors and filled with lively fish — signal that a San Juan-type disaster may be unlikely in Aspen.
Tim Willoughby’s family story parallels Aspen’s. He began sharing folklore while teaching for Aspen Country Day School and Colorado Mountain College. Now a tourist in his native town, he views it with historical perspective. Reach him at email@example.com.
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