Kerr Dam

excerpt from:
Kerr Dam: All you want to know….
Justin Foust and Benett Kruttoff

Standing fifty-four feet taller than Niagara Falls, Kerr Dam is a very interesting place to visit. The dam was started in 1929, by Rocky Mountain Power and although the actual construction time was three or four years, because of the lack of money during the depression, construction was halted a few times before the had the dam ready for operation in 1938. The dam has influenced the economy from the beginning. It produces power from Kalispell to Missoula and produces electricity for irrigation and improved farm productivity.

Kerr Dam is located eight miles south of Polson on the Flathead River, and it has played an important role in the Flathead Valley’s economy. It provided many jobs during construction when work in the area was sometimes hard to find, and today Kerr still puts a lot of money into the community. It is the largest electrical generating power plant in the Montana Power Company system. The dam is 204 feet high, 450 feet long at the top, 100 feet long at the base, containing 85,000 cubic yards of concrete. The dam storage of water amounts to 1,217,000 acre/ft. The water is kept at an elevation between 2,883ft and 2,893ft above sea level. Its total capacity is 190,000 kilowatts, or 190 mega-watts. (Bergman & McAlear). When the dam was finished it consisted of one powerhouse and on generator. According to Lloyd Turnage, one of four employers, the dam consists of three generators and one powerhouse.

Kerr Dam was built as a gravity dam, which is a solid concrete structure with triangular cross sections. The dam is thick at its base and thinner towards its top. When seen from the top it is slightly curved and the upper side of the dam is vertical. It depends primarily on its own weight for stability and has the least maintenance compared to arch dams, buttress dams, or embankment dams (Microsoft, Encarta).

When building a dam, water leakage through or under a dam must be prevented to avoid water loss or to prevent erosion in the dam structure. Engineers must consider gravity (which pulls the dam down), water pressure behind the dam, earthquakes, ice pressure, and earth stresses and tensions. When starting construction, water must be moved around the work site. Cofferdams are used to exclude water from the dam site during construction. A cofferdam is earth embankment that merges water around the site. (Microsoft, Encarta).

The height of the dam, which is 204 ft, was limited by the topography of the dam location. Outlet works are necessary so that water can be drawn continuously from reservoirs. To get power out of the dam, the water flowing out of the spillways is run through generators to produce electrical power (Microsoft, Encarta).

Construction of Kerr Dam began on May 23, 1930, by Rocky Mountain Power. Kerr Dam was named after Frank A. Kerr, who was the president of MPC. On July 1, 1931 the depression caused money and funding to dry up, so construction stalled for five years. In 1936 the construction of the dam was resumed by Montana Power, and in August 6, 1938 the dam was completed. It consisted of one unit and a powerhouse. All in all it took around three years to construct. ( Turnage and Faughleberg).

At peak construction 1,200 men were employed. The higher skilled workers earned a couple of dollars an hour, while the lower skilled workers earned around forty to fifty cents an hour. There were no major problems with the dam during construction, but around fourteen deaths occurred among workers who were involved in the construction of the dam (Turnage).

The Dam was operated on an annually renewable license between 1980 and 1985. In 1985 the Confederate Salish Kootenai tribes and the utility agreed to a new contract which was approved by the Federal Energy Regulatory Commission (FERC). To start the new FERC license the new agreement provided for a $ 9 million annual rental fee paid to the tribe from the dam's earnings (Faughleberg).

Many people felt that the construction of the dam was a plus. It created jobs and brought money into our economy. The developments of the power site proceeded the opening of the reservation to homesteading. The only people that might not have liked it would have been the Confederate Salish and Kootenai Tribes because it effects the fisheries and the flow of the river. One thing that the tribes can't argue with is the large amount of rent paid to them yearly by the dam's income. Currently, they are paid around 14 million a year (Turnage).

The assessed value of the dam's productivity of electricity is estimated at $9,656,714. Lake County receives thirty percent of this amount, which is thirteen, and a half percent of the total tax load of Lake County. The total valuation by Montana Power Company is around $30,000,000 (Bergman & McAlear).