The Milltown Dam's powerhouse produced electricity for nearly a century. It was removed in 2008 as part of the Superfund remediation of the Milltown site. Numerous artifacts, inlcuding a generator, have been set aside for future use in an interpretive display.

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For more on the dam and powerhouse, see the Historic American Engineering Record for the Milltown Dam at the website of the Built in America Collection at the Library of Congress.

In 1904 John McCormick sold his river bottom ranch at the confluence of the Blackfoot and Clark Fork Rivers to a land company owned by Montana’s U.S Senator, William A. Clark.  At the confluence of the two rivers, Clark saw an opportunity to dam the flow and create electricity for local mills and the bustling neighbor downstream, the city of Missoula.

W.A. Clark’s engineers from Butte originally showed two locations for the dam.  In September 1905, A. H. Wethey, a partner in the Western Lumber Company, secured water rights for the dam--12,000 cubic feet on the Big Blackfoot in December 1904 and 24,000 cubic feet on the Missoula River.  Some of the land for the dam came from the Bandmann Ranch.

Construction of the Milltown Dam. Construction of the dam on the Missoula River began Friday, September 13, 1905.  Clark apparently stopped construction in November with thoughts of expanding the dam, but it was resumed the next year as before.  Completion of the dam occurred near the end of 1907, and the gates of the dam were closed for the first time on January 5, 1908.  The Missoulian noted that the backwater extended up the Blackfoot covering the old county road to a depth of 12 feet in one spot.  This may have been an effort on Clark's part to cause damage to the Bonner dam upstream, which was owned by his rival.

A party of dignitaries including A.H. Wethey representing Clark’s interests, arrived at the power house on January 9, 1908, to see the lights turned on for the first time.  Clark apparently did not attend this memorable occasion, but Wethey was impressed, saying, "It has been a tremendous undertaking and the work has continued with slight interruptions for the past two and a half years.  The cost of the plant complete will aggregate $400,000…Electricity is a wonderful thing and wherever power plants are introduced there seems to be no limit to the wonderful possibilities that can be accompanied with this great power."

As reported by Dam Superintendent George Slack, materials used in the dam construction included 2 million feet of timber, 5000 barrels of cement, thousands of tons of granite, hundreds of tons of structural steel, 125 acres of land cleared of timber and stumpage, over 600 acres of former agricultural land flooded, and 50 workers on the payroll.

Slack noted that an outlet on the opposite side of the spillway would carry irrigation water to the Bandmann Ranch (Bandmann had sold Clark some of the land needed for the dam), and a fish ladder would be constructed near that outlet.  He added, "…when the last piece of timber is added to the dam it will be in such condition that the highest waters known in this vicinity will not affect it in the least."  His statement was proven wrong by the flood waters that same year, in June 1908.

The dam, not of unusual design, was a timber-crib, rock-filled, 40-foot dam 219 feet long.  The sluice gate section, about 52 feet, was also timber-crib originally, but was later replaced by concrete.  The power house was brick and reinforced concrete with 18-inch walls.  A suspension bridge spans the spillway.  The powerhouse contained five General Electric alternating generators and two General Electric  direct current exciters, two of which still had their original Woodward governors in 2008. The generators were powered by Leffel twin turbines.  At peak generation, the dam was capable of supplying 3,400 kilowatts of power.  It was known as a ”run of the river” dam; the amount of power it can produce is determined by the amount of water flowing in the river.  It also has no flood control, an issue that would soon come to haunt it.  The interior workings of the dam changed little after it was constructed in 1908.

After it was built, the dam employed only a few people, compared to the hundreds of men employed by the lumber mill.  There were four houses on the dam's property for the employees.  Today, only the garages of two remain.  Interestingly Clark employed no outside workers in designing and constructing the dam; he brought them all from other Butte operations.

Originally the power produced by the dam was used by the Western Lumber Mill; the communities of Bonner, Milltown, and Missoula; the street car; and even some areas in the Bitterroot Valley. The dam operator would direct current by means of switches located on the second floor of the power house.  By 2008, the switches were gone, and the power fed into the grid, controlled from Butte.

Over the years there were some changes and updating of the operations at the dam including the concrete sluice gates, and additional turbines. The dam itself was owned by a variety of Clark businesses, all with interlocking directorates. After Clark's death, Montana Power acquired the dam from his heirs in 1929.  In the Story of Montana Power, a blurb for the year 1929 notes only that, "The Company acquired by purchase the small hydroelectric station on the Missoula River and the distribution system in Missoula and the Bitterroot Valley."

Montana Power Company (MPC) had been created in 1912 with the merger of four electric companies.  John D. Ryan, who happened to also be president of Amalgamated Copper and later ACM, was largely responsible for the merger.  With Clark’s dam, MPC owned all the existing hydroelectric stations in Montana.  Ryan remained president of MPC until his  death in 1933.

 

It had been a cold, wet May and the ground in early June was saturated from three weeks of hard steady rains. Butte had already seen seven inches of rain and on June 6th  the temperature dropped and nine inches of snow fell on the city. As it melted, the soaked earth soon flooded.

A  century ago,  the Clark Fork and Blackfoot Rivers saw their greatest flood in recorded history. The rains and snow of 1908 sent torrents into the two rivers. By early June the Clark Fork River hit a record of nearly 17 and a half feet – a full 4 and a half feet above major flood stage. It wreaked havoc on western Montana. Residents along the river fled with the rise of the water. Bridges washed out. The high flows shut down the rail lines as tracks flooded or were buried in landslides, leaving thousands of passengers stranded. The mines in Butte, unable to ship ore by rail, were closed. 1908 was an election year as well, and the state’s Democratic Convention had to be postponed.

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Along the Big Blackfoot River fears mounted over a log raft of some 50 million feet of lumber that was held behind the Bonner Dam. Just downstream, raging flows tested what was then called Clark’s Dam. Rumors abounded in Missoula about whether the new structure was about to give way.

Completed just six months earlier, the dam built by then Sen. William A Clark and was considered state-of-the-art. Into its construction went two million feet of timbers, 5000 barrels of cement, hundreds of tons of structural steel and untold thousands of tons of granite. The Missoulian reported that “No expense was spared in making the dam one of the strongest of its kind, and … enough power will be generated to furnish the entire western portion of the state with electricity for all purposes.”

Still the project engineers couldn’t have forseen the estimated the 48,000 cubic feet per second that gushed over the dam’s spillway in June of 1908. Clark’s workers reportedly attempted to dynamite the south side of the dam to relieve pressure but to no effect. The dam, nonetheless, according to one observer,  was “as solid as a rock,” The powerhouse, however, was flooded to a depth of ten feet, cutting off electricity for more than two weeks.

In the local press, Clark’s representatives steadfastly proclaimed the dam’s safety and bemoaned the circulation of rumors. “There is no more danger of the power dam going out,” said one of Clark’s officials, “than there is of the mountains washing down into the river.” Indeed he was correct about the dam holding, though it did require substantial rebuilding, but he proved quite wrong on the second assertion. Mountains along the Continental Divide, crushed and stripped of precious metals, did wash into the river as mine waste, strewing contamination from the headwaters of Silver Bow Creek on down the Clark Fork.

With those historic flows came the moment of origin of the Milltown Reservoir Superfund site, which stretches along 120 miles of river making it one of the largest in the nation. The great flood left more than 6.6 million cubic yards of waste, laden with heavy metals and arsenic, in the sediment behind the Dam. These toxic sediments poisoned the aquifer that was used by Milltown residents for generations before its designation as a Superfund site in 1983.

An aerial photo of the Milltown Reservoir from the late 1930s.

In a span of 25 years, both the Blackfoot and Clark Fork Rivers were dammed and put to industrial use. The Bonner Dam was finished in 1886 and the Milltown Dam was completed in 1908.

The Bonner Dam was removed in 2005 and the Milltown Dam's removal began  in 2008.

 

Bonner Dam on the Blackfoot River in 1891 In September 1884 the Montana Improvement Company announced plans to build a 200-foot dam on the Big Blackfoot River, as it was known, to hold logs that would be cut from lands up the Blackfoot. First they would collect a supply of logs in the river and then build a mill (or a series of mills from there to Missoula). Missoulians were excited at the prospect of economic boom for their community.

The dam was constructed by another of Hammond’s relatives, his maternal uncle, Walter Coombes. The initial dam structure did not survive the spring floods of 1885, but it was rebuilt in time for the opening of the mill in 1886. In the spring of 1886, it held 20,000 board feet of lumber behind it. A steam-powered generator and a water powered turbine generated electricity for the mill itself. Power generation was limited to the mill lights. Missoula interests were soon to eye the potential the water power at the dam offered for their growing electric needs.

The first electric plant in Missoula was built in 1889 by A. B. Hammond for the Missoula Mercantile and First National Bank, both of which he owned, as well as the Florence Hotel. In 1890 H.M. Ogden produced 220 volts to power his flour mill at the north end of the Higgins Avenue Bridge. Within a couple of years another enterprise built a steam plant on the adjacent island in the Clark Fork, bringing lights to theaters, saloons, and stores on Higgins Avenue.

In 1895, ownership of generating facilities passed from still another owner, Northwest General Electric, to Hammond's newly incorporated company, Missoula Light and Power (ML&P). Hammond then proceeded to merge this company with the existing water service. In 1898, after obtaining an acre of land from the Big Blackfoot Milling Company for $1, ML&P constructed a powerhouse adjacent to the Bonner mill. This electric generating station sent 3,400 volts to Missoula, replacing the previous generation facility on the island in Missoula.

After Clark's Dam was completed in 1908, the Bonner Dam’s power component was no longer used to supply electricity to Missoula. Clark’s Dam produced much more electricity, and at full pool the new dam just about inundated the older dam. This is clearly shown in Clark’s engineering drawings. Clark purchased Hammond’s Missoula Light and Power in 1906, so he owned both facilities by the time the dam was in operation.

The Bonner Dam was removed in 2007 as part of the Federal Superfund cleanup of the Milltown Dam site.