Patagonia mines oozed high levels of iron, US says

Levels of iron that created orange runoff from two old Patagonia-area mines this fall were very high, “way above any standards,” says a federal geologist.

The iron and other contaminants were flushed out of the Lead Queen and Trench mines into neighboring creeks in September and October, the U.S. Geological Survey has said. The iron gave the runoff a bright, orange-colored appearance that caught the attention of area residents and state and federal scientists. The high iron readings were found in samples at the two sites that were taken this fall by the USGS shortly after the orange gunk started appearing.

“This iron was way above a whole range of standards,” said Floyd Gray, a USGS research geologist in Tucson.

He said such levels hadn’t turned up in the neighboring creeks in at least 10 years and in fact had never been documented at such levels, although authorities assumed the iron had been in the creeks at those levels before.

The U.S. Forest Service, which owns the Lead Queen mine site lying on federal land, hope to start some cleanup work at the site by spring 2015, a service official says. The Arizona Department of Environmental Quality, which has cited owners of the Trench Mine for six violations of state water quality rules, referred questions on remediation of that site to the owner — the Asarco Multi-State Trust. Andrew Steinberg, the trust’s vice president for operations, didn’t return calls from the Star last week about the Trench site.

The USGS took samples near where the pollution was flushed out of the two mine areas into a small creek near Lead Queen and Alum Gulch near the Trench Mine. The two mine sites lie about six and 12 miles south of Patagonia, respectively. Their impacts on the neighboring creeks has caused an uproar among opponents of a proposed silver mine slated for the Patagonia Mountains.

The gulch and the creek near Lead Queen are tributaries to Harshaw Creek, which in turn feeds Sonoita Creek, at a spot upstream of a major bird sanctuary at the neighboring Patagonia-Sonoita Creek Preserve, run by the Nature Conservancy. Officials found no evidence of iron contamination in Harshaw or Sonoita Creek, Gray said, and they suspect that the heavy iron dropped out of the creek within a mile of where it left the mine site.

But it’s possible that the iron, now lodged in the underlying soils, could be washed downstream into Harshaw or Sonoita creeks during next summer’s monsoons, he said.

The Lead Queen Mine has been closed since the 1940s. The Trench Mine was operated by the mining giant Asarco from 1939 to 1957 and was reclaimed from 1989 to 1991, archives on file with the Arizona Geological Survey show.

The Lead Queen’s contamination was caused by iron that had built up for decades in a tunnel system going at least several hundred feet back and underneath a nearby ridgetop. It was suddenly flushed into the open by this September’s monsoon storms, said the USGS’s Gray, who has monitored this area extensively.

The Trench Mine’s contamination was sparked by flooding that pushed out iron and other minerals and metals from underneath mine tailings — and that also caused a breach of the tailings, Gray said.

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“It was like a bathtub overspilling,” Gray said.

Complete results of the USGS’s data sampling will be available next year. The iron releases from the sites were unusual in scale but the releases of heavy metals, while still problematic, were little different than what’s gone down those creeks for a century, Gray said. A white milky substance in the water indicated high levels of the metal aluminum, at levels typical of what’s seen in runoff such as this that’s also acidic, he said.

“We found a bunch of stuff. This happens in every monsoon except the iron doesn’t happen in every monsoon,” Gray said recently. “The only thing new was this iron flush — the sludge.”

The orange sludge came from the Lead Queen Mine on Forest Service land, Gray said. From the Trench Mine, reddish brown to orange runoff also was a factor, although it didn’t come in the form of sludge, Gray said.

The Arizona DEQ has said it doesn’t believe the mine itself contaminated the neighboring stream, and that the reddish-brown material in the Alum Gulch came from a wetlands outside the mine site. Gray and local Patagonia area residents have disputed that point.

The Trench Mine history on file with the Arizona Geological Survey indicates that the mine site included four tailings ponds and shows the reclamation of the mine site included the planting of numerous grass species at wetlands there, Gray said. ADEQ officials have said those wetlands aren’t part of the site for which the Asarco mine trust now has responsibility.

Forest Service officials “are going to take a closer look” this year at how to clean up the Lead Queen site, said Eli Curiel, a Coronado National Forest environmental engineer.

“We’re coming up with some ideas. I have folks coming in from the Phoenix area. It’s just going to take a couple of months to put some (projects) out to bid, to do on-the-ground remediation,” Curiel said in an interview.

The work probably will involve stabilization of the site and removal of contaminated material, Curiel said.

“I’m not sure about which route we’re going to go at this point,” he said. “ We’re looking at several options.”

The area around the mine is geologically complex, with a lot of underground faults “that we can’t see and have no control over,” Curiel said. “We’ll deal with things that we can control — mine adits (long, sloping tunnels created to drain water from mines), shafts and stuff that’s in the drainage.”