SILVERTON - Mine remediation and greater monitoring above Silverton this summer will help ease the level of poisonous metals in the Animas River, at least at first.

At the Red and Bonita Mine, where polluted water is pouring out at 500 gallons per minute, Environmental Protection Agency workers would like to put a stop to the flow by September, said Steven Way, on-scene coordinator for the agency.

About 18 percent of the heavy metals in the Animas River come from the mine, said Peter Butler, co-coordinator of the Animas River Stakeholder Group.

It is contributing cadmium, zinc, iron and aluminum to the river, which are responsible for killing off native fish and other species.

The $1.5 million construction project is set to start in mid-July, and it will require workers to muck out nontoxic mineral deposits from the floor of the mine before installing a concrete bulkhead. It is not a Superfund project, but the EPA plans to pay for it, Way said.

Red and Bonita began draining in 2006 after the Sunnyside Gold Corp., the last major mining operation in Silverton, plugged the American Tunnel in three places. The small Red and Bonita Mine, founded in the 1800s, was never productive.

The EPA understands that this new bulkhead could have the same effect as the American Tunnel bulkheads and cause water to drain from other mines. As a result, the agency plans to monitor the Gold King No. 7 level and the Mogul because they are both nearby, Way said.

Gold King No. 7, which is partially collapsed, will be stabilized this summer to allow for better monitoring of flows, he said.

Right after the Red and Bonita is plugged, there will be an improvement in water quality, but it doesn't last or water quality worsens, the bulkhead will have a valve so the EPA can open it up again, Way said.

"This, in a way, is as much as experiment as the American Tunnel," said Steve Fearn, co-coordinator of the Animas River Stakeholders Group.

The idea behind a bulkhead is to return water to its natural path. When water can percolate through the soil and rock slowly, it carries much less metal down to the Animas River, Way said.

The region around Silverton is naturally rich in metals. So it is difficult to determine how much dissolved metal was in the creeks and rivers before it was disturbed by mining.

"It's been bleeding out of the mountains for a long time," Way said.

The idea is to improve water quality, but it is likely impossible to eliminate the metal in the water.

"There's no expectation we're going to see a bunch of fish swimming up Cement Creek," he said.

If the Red and Bonita bulkhead doesn't work, it may be cause to look more seriously at water treatment, Butler said.

Sunnyside Gold Corp. was treating about 1,600 gallons of water per minute up until the early 2000s, and it had a positive impact.

Permanent water treatment is expensive, and the Animas River Stakeholders Group, which includes the EPA, has been focused on more short-term projects. For example, this summer the group plans to move and cover a tailings pile near the Bullion King Mine. The waste will be covered with plastic to keep it out of the watershed, said Kirstin Brown, with the Colorado Division of Reclamation, Mining and Safety.

In another area, Sunnyside Gold Corp. is looking into how groundwater might be contributing to the problem. The company is voluntarily doing the study at the request of EPA and other agencies, said Larry Perino, reclamation manager for the company.

This year, the company plans to try to find the underground paths water is taking to join the Animas River between Howardsville and Cement Creek, Perino said.

This stretch of river runs along Sunnyside's dry settling ponds, and the river picks up more metals along this stretch in March and April during runoff, Butler said.

But it is unknown where those metals are coming from, and Perino couldn't say what might be done if groundwater was found running through the ponds full of tailings.

Regardless of the outcomes of the groundwater study and the Red and Bonita monitoring results, the efforts will add to a greater understanding of complex water drainages.

"A year from now, we might know a lot more than we do now," Butler said.

mshinn@durangoherald.com