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60 YEARS AGO • MAY 29, 1958

HIGH WATER DAMAGES DAM, TAKES OUT BRIDGE

Immediate danger to the Montana Power Co. dam at Thompson Falls has subsided considerably Wednesday following a serious threat to the dam Saturday and Sunday after the boom broke about 7 o’clock Saturday morning and crashed into the main spillway section of the dam.

Flow of the Clark Fork River reached its highest point Monday afternoon at 96,250, Clarence Helman stated.

After breaking the boom and damaging the bent at the extreme left side of the dam Saturday the swollen river tore out a 158-foot section of the 400-foot service bridge located about 600 feet below the Noxon Rapids dam. The bridge was built by Morrison-Knudson for use during the construction period at the dam.

The high water also caused M-K to halt placement of concrete in the dam because of the great strain to the trestle legs in the spillway section during the high runoff. M-K officials feel that operation of the whirley cranes for pouring concrete during the high water could increase the vibration and strain on trestle legs to a danger point.

The two huge cranes are being kept on separate sides of the dam so as not to add any more strain on that section of the trestle.

M-K plans to resume pouring of concrete again Monday if the river flow has dropped sufficiently. As you, my readers, may have surmised, the Noxon Dam was being constructed at this time.

Here at Thompson Falls, watchmen are remaining on duty at night to maintain a constant check on conditions at the dam the local power company’s crew is working during the day to remove logs and debris from the spillway section.

At the height of the danger Saturday, heavy equipment was brought in by M-K from Noxon Rapids to aid in removing the boom, which was blocking the main spillway and collecting debris to increase pressure on the dam. When the boom jackknifed into the dam it bent one main steel girder and caused the deck surface at that point to drop about 1½ feet. Steel on the lower side of the dam was not damaged, Helman said.

A portion of the boom was pulled from the river by bulldozers operated by Ed Muster and Lester Schmoyer. Other sections were cut loose and permitted to flow over the dam.

The boom consists of two 18 by 18-inch timbers lashed to steel air tanks with log chains. A two-inch steel cable connected the sections of the boom. It was a break in the cable which permitted the boom to crash into the spillway bents and piers.

The efforts of Montana Power Co. employees and other residents recruited locally Saturday drew a large crowd of onlookers to both shores of the reservoir all day Saturday.

Helman said the Missoula river peaked Saturday and has been dropping since, easing the situation here. Additional water is expected from Flathead Lake, however.

Monday’s top flow of 96,250 is considerably below the peak of 165,000 reached during the 1948 flood before construction of Hungry Horse and Kerr dams.

80 YEARS AGO • JUNE 1, 1938

HIGH WATER NEARS ITS PEAK

The Clarks Fork is now a raging torrent of water, with the runoff from the Bitterroot, St. Regis, Flathead, North Fork and a hundred other tributary streams coming down from the high mountain drainage, flowing over the dam at Thompson Falls.

The flow at present is 97,000 cubic feet per second. This is a tremendous flow of water, more than we have experienced in years. But the water is not nearly as high as some high water flood stages in the past. In 1923, 1928 and 1933 and other years the crest reached 130,000 to 136,000 cubic feet per second, equal to the average flow of Niagara. Of course, the full crest of the flood has not yet been reached, but it is not likely to exceed 110,000, according to experts.

The high water of 1904 is the year of all time record. That spring the flood reached a crest of 230,000 cubic feet per second. That was before the dam was built. If we ever should experience a flood like that again it might imperil great hydro-electric dam sites, jamming logs and debris against them. Just as a precaution all the elaborate methods of protection to the dam at Thompson Falls are used. Men guard the boom to shoot big logs and debris through the spillway so the logs will not jam up in the steel structure. Lights glare all night, and search lights swing over the fast flowing water. Men guard the dam by three shifts, and a boat crew is in operation. There are approximately twenty-five men working on the high water shifts.

The high water of 1904, according to Mr. Strong of the Forest Service, was really two winters snows in one. During the winter of 1902 and 1903, the snow never melted on the high peaks and high mountain country. During the winters of 1903 and 1904 the precipitation and snow were unusually heavy. In the spring it warmed up suddenly and two seasons run off of snow melted at once. All railroad right-of-way trackage is based upon the level of the 1904 flood.

As of Tuesday, the Clark Fork River was at 92,300 cubic feet per second and the river is expected to crest on Thursday.

 

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