The effort to clean up mining wastes in the headwaters of the Blackfoot River is moving forward, after U.S. District Court Judge Donald Molloy agreed with a proposed settlement.

The surprisingly fast track for the settlement is appreciated by the Helena National Forest, especially since the agency recently stacked 300 sandbags along a diversion ditch built last fall as a means to prevent a blowout of an earthen dam — known as an impoundment — in the area. The last time the impoundment gave way in 1975, all aquatic life was killed along a 10-mile stretch of the fabled Blackfoot River.

“The ditch collapsed in a couple of places, and we had to rebuild it with sandbags,” Lincoln District Ranger Amber Kamps said on Monday. “Everything looks good now — the water level behind the impoundment is receding — but this makes me want to move forward as quickly as we can.”

In his one-page order dated last Thursday, Molloy wrote that he approves of a $37 million settlement agreement lodged in his court April 25 by the United States and State of Montana against Asarco and Atlantic Richfield Co., or Arco. Texas Bankruptcy Court Judge Richard S. Schmidt signed a similar order May 21.

Asarco and Arco will each pay the state $8 million for the Upper Blackfoot Mining Complex cleanup under the agreement, which also notes that the state will receive an additional $19.77 million from Asarco, and the federal government will get $1 million to oversee the state implementation of the cleanup effort. The federal government also will receive $230,000 for past costs.

A large chunk of the money will be used to remove the impoundment, which was built with contaminated mill tailings. Water passing through the structure, and held behind it, is laced with high levels of aluminum, arsenic, zinc and iron, among other heavy metals.

Previously, state officials said they didn’t expect the two courts’ approval until late June or possibly July. The agreement was reached through the Montana departments of Justice and Environmental Quality, and the federal Forest Service and Department of Justice.

“The state and the federal government are very pleased, if not a little surprised, that this settlement moved swiftly, without objection, through the approval process in both the Texas and Montana courts,” Rob Collins, an attorney with the state Department of Justice’s Natural Resource Damage Program, said on Monday. “Once we receive the initial cash payments, we can begin project design.”

Collins said that in 60 days, the state will withdraw its court action and the agreement will become effective. Within 20 days of that withdrawal, the state will receive the first $16 million cash payment, evenly split by Asarco and Arco, and the federal government will receive its $1 million for oversight.

However, the rest of the money — $20 million — won’t be paid until Asarco’s bankruptcy reorganization plan is in place.

Still, both Kamps and Collins said the federal and state agencies are hoping the project to remove the contaminated sediments behind the Mike Horse Dam, as well as the impoundment itself, can begin during the next field season.

The dam sits on Forest Service land bout 15 miles east of Lincoln. Last fall the water behind the dam, as well as Beartrap Creek, which runs into the impoundment, were rerouted through a new ditch. This drained the pool and reduced the likelihood of a blowout similar to what happened in 1975.

But Kamps said there apparently are underground springs in the area, and they began refilling the impoundment around Memorial Day weekend. That was about the same time heavy rains coupled with the springtime runoff put pressure on the ditch, which is similar to what happened preceding the 1975 blowout.

The original dam was rebuilt shortly after the blowout, but three years ago questions arose regarding its stability, and an investigation revealed large holes, or “voids” in the structure. The Forest Service reported that the dam was a compromised structure that should be removed from service.

Kamps said the discovery of the underground springs this year probably is a good thing, since they’ll need to be taken into account during the cleanup’s design and engineering phase. She added that the Forest Service is doing additional monitoring as snow continues to melt from the mountain ranges, swelling many streams in Montana.

Asarco is considered a responsible party for the contamination since the company engaged in mining and milling activities in the upper Blackfoot headwaters area from 1889 through the 1960s, pulling silver, zinc and lead from the Mike Horse Mine. Tailings from the mine work created the original dam.

A predecessor of Arco assumed a lease to a number of patented and unpatented mining claims at the mining complex site in 1964, and repaired the Mike Horse Dam when it failed in 1975.

Asarco also owns the mothballed East Helena lead smelter, as well as other properties throughout the nation, and is trying to reorganize and emerge from Chapter 11 bankruptcy, which it filed for in August 2005.

Reporter Eve Byron: 447-4076 or eve.byron@helenair.com