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Removing The Dam At Milltown, Montana

The federal Environmental Protection Agency expects Milltown Dam to be dismantled in the winter of 2006-2007. Then comes the disposal of 6,600,000 cubic yards of toxic waste mud from 160 years of mining and smelting in Butte and Anaconda, 120 miles up the Clark Fork River. About one third, or 2,200,000 cubic yards will be hauled by rail 100 miles up to the Opportunity settling ponds near the old smelter at Anaconda. In 1979, Atlantic Richfield Co. (ARCO-BP) purchased the assets and liabilities of the Anaconda Mining Co. (ACM) and gained ownership of the toxic mud behind the dam. ARCO will pay $80,000,000, Northwestern Energy Corp. (NWE), who owns the dam, will pay $11,400,000 and the state will pay $7,600,000 from a $225,000,000 settlement that ARCO and Montana State reached in 1998 for damage to natural resources. The agreement for all of this was filed in U.S. District Court in Missoula and coordinated by the federal Environmental Protection Agency. The project involves NWE. and its Clark Fork and Blackfoot LLC subsidiary as the dam’s owner, and ARCO as owner of the mines and smelters that created the toxic sediments.

The EPA’s clean-up plan covers 120 river miles upstream of Milltown Dam, one of the largest Superfund sites in the nation. The stretch of the Clark Fork River from Warm Springs to Drummond is contaminated with cadmium, arsenic, lead, copper and zinc. The cleanup will remove 167 acres of polluted soils along the river, treat 700 acres of soil in place, establish a 50-ft. riparian area on each side, replant native willows, dogwood and cottonwood to stabilize 56 miles of stream bank against further erosion and prevent additional heavy toxic metals from entering the river. The entire clean-up will take 10 years. When all is completed, our integrity will be restored. This is a classic case of “sins of our fathers levied on the backs of their children.”

Business Deals

Ever since ARCO-BP purchased the ACM in 1977 and realized the purchase was a classic business blunder, they have been debating their responsibility. A secret agreement between ACM and ARCO-BP was made to keep the dam in place, reinforced with an inflatable rubber bladder, leaving the toxic sediments behind the dam in place forever. What corporation will be in business forever to take care of a faulty dam? They would use the FERC licensing process to support their goal. The scheme called for the ownership of the dam to be transferred to a third-party limited liability corporation of $12 million for the dam’s operation. NWE was forced to buy the dam from Montana Power Company (MPC) when they bought the electric & gas transmission system from them. Originally, MPC tried to give the dam away, but had no takers. NWE was not allowed to limit its liability in a Delaware bankruptcy court. Sidewinding their way out of responsibility is a sad track record of corporations.

Dam Structure

Milltown Dam was built in 1906 by magnate William Clark to generate power for his sawmills at Milltown and Bonner. Montana Power Co. had its start here, as a subsidiary of mining activities, producing mine tunnel props for Butte. On November 10, 2000, cracks and voids of 12 to 18 inches were found in the dam and spillway. Water was seeping through and displacing fill, and settling indicated a catastrophic dam failure. Federal Energy Regulatory Commission (FERC) which licenses the nation’s dams on navigable streams, classified it as “high hazard to collapse” and directed the dam be reinforced to withstand a flood of 127,000 cfs. Such a flood is easily possible considering the amount of denuded land in the two river drainage's above the dam. If flood, ice jam or earthquake would breach the dam, 6,600,000 cubic yards of toxic sediment would poison aquatic, terrestrial and human life downriver into Idaho’s Lake Pend Oreille. Surely Idaho would then sue Montana for damage and clean-up costs.

Ice Jam of 1996

During the winter of 1996, a massive, glacier-like ice jam ominously descended the Blackfoot River’s narrow canyon. Passing Milltown it threatened to break the dam, releasing its toxic contents. Feverish activity resulted in an emergency release of water so the ice jam would grind to a stop on the riverbed. A large amount of sediment also flushed downriver, raising copper concentrations to 770 ppb where state standards allow 18 ppb. Fifty percent of the fish downstream died. Studies reveal that probably only 20% of the river’s fish populations survive to this day.

Water Wells Contaminated

In 1981, the Missoula City/County Health Department informed the residents of Milltown, Bonner and Piltzville that their wells were contaminated with over 10 times the amount of arsenic that federal drinking water standards allow. Leaching from behind the dam are toxic mining sediments of copper, zinc, cadmium, lead and arsenic which are strongly linked to bladder, lung and kidney cancer. Wells were shut down and bottled water distributed.

Dam Removal

On October 17, 2005, work was started on removal of Stimson Lumber Co.’s dam, built in 1886 as a way to stop floating log drives down the Blackfoot River at Bonner. The 30 ft. tall, 210 ft. long rock-filled timber crib dam has been mostly immersed since the Milltown Dam was built, but as Milltown Dam is drawn down 8 ft. in preparation for its removal, the Stimson Dam rises from the past. Dismantling of the Stimson Dam was begun on the edge closest to the mill, with water diverted through a new channel. Then the entire dam was removed by the end of November, 2005. If the Stimson Dam had been left in place, it would have become unstable following the removal of Milltown Dam and the resumption of a free flowing Blackfoot River.

NWE has asked FERC for permission to begin removing Milltown Dam by first lowering the water level 10 ft. beginning December, 2005. Then work would begin by building a bypass channel around the dam, where the river would be held temporarily while the dam is removed and 2,600,000 cubic yards of heavy metal contaminated sediments are excavated from the reservoir and transported by rail to the Opportunity ponds, which were used by ACM as settling ponds for smelter waste. These are no longer ponds but 7 square miles of mining waste 5 to 10 ft. high, containing high levels of copper, lead, cadmium, zinc, mercury and arsenic. Eventually a natural river channel will be constructed through the old reservoir and pass the tilted rock fault where the dam has blocked the Clark Fork River for 100 years.

When a dam is taken out, sediments are redistributed and that means trouble for aquatic life downstream. Some of the heavy metals will settle in the rocks in stream bottoms and release their toxins over time. Vegetation grows in former reservoirs, but during high water heavy metals will slowly move downstream and hammer resident fish.

Community of Opportunity

The Opportunity Citizens Protection Association is concerned about the dumping of 2,600,000 cubic yards of wet toxic sediments on top of the dry Opportunity settling ponds used after the Anaconda smelter was built. The sediments would come from Milltown Dam, returning them to the area they originated from. Opportunity’s 280 households draw drinking water from private wells and are bounded on the north and west by the dry settling ponds. The Association wants ARCO to connect them to Anaconda’s municipal water system, 6 miles to the west. ARCO says the community’s request is not justified. The Opportunity folks are already at risk from past dumping and recently have received toxic waste from clean-up of historic mines. Now, still to come, are train loads of Milltown Dam toxic mud. Groundwater around Opportunity is contaminated and concerns are real.


For the first time in over 100 years, the Clark Fork and Blackfoot Rivers above Thompson Falls Dam will run free without blockage. The dismantling of the Milltown Dam on the Clark Fork, and the Stimson Dam on the Blackfoot, will open the two river systems to migrating fish up to their sources. Milltown Dam, originally built for power generation, and Stimson Dam, built to stop logs from log drives, became a liability to communities along the rivers. Neither dam provided useful water storage or electricity generation and prevented fish passage to their historic spawning grounds on tributaries. Restoring bull and cutthroat trout populations and restoring floating through the Milltown Dam site will go a long way to restoring our self respect and resolving to never again allow a corporation to “lock a copper collar around our necks.” ~

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