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Frenchtown Project History (46 KB) (pdf)
General Description| Plan| Development| Benefits

General Description

The Frenchtown Project consists of Frenchtown Diversion Dam on a side channel of the Clark Fork River, and a gravity-flow distribution system that includes 17 miles of main canal and 21 miles of laterals. The system diverts water from the river to now irrigate approximately 5,000 acres of land between Grass Valley and Huson, Montana; some 500 acres have been added in recent years. An ample supply of water makes storage unnecessary.

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Water diverted from Clark Fork River is carried through a gravity distribution system which originates at Frenchtown Diversion Dam.

Facility Descriptions

Frenchtown Diversion Dam

The Frenchtown Diversion Dam, an earth and rockfill structure, is on a side channel of the Clark Fork River about 6 miles west of Missoula, Montana. The dam is 16 feet high, has a crest length of 489 feet, and contains 12,000 cubic yards of material. Two 4-foot-square gates control the canal headworks, which has a capacity of 170 cubic feet per second.

Main Canal and Distribution System

The Main Canal originates at the Frenchtown Diversion Dam and extends 17 miles along the northeast side of the Clark Fork River to a point near Huson. The canal has an initial capacity of 170 cubic feet per second. Laterals distribute the water to the project lands. Most of the lands are sprinkler irrigated; only one 50-acre tract is gravity irrigated.

Operating Agencies

The project has been operated and maintained by the Frenchtown Irrigation District since December 31, 1938.

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The lands of the project were settled in 1860 by French-Canadian immigrants. The farms were operated without irrigation and with varying degrees of success until the irrigation features of the project were completed.


Although the Reclamation Service and a consulting engineer studied the irrigation possibilities in the valley as early as 1919, it was not until 1935 that a concerted effort was made by local farmers to develop an irrigation project. In 1935, the farmers organized the Frenchtown Irrigation District and petitioned the Bureau of Reclamation for assistance in developing irrigation. Further studies were made, and after it was found feasible, the project was authorized.


The Frenchtown Project was found feasible by the Secretary of the Interior on September 11, 1935, and approved by the President on September 21, 1935, pursuant to section 4 of the Act of June 25, 1910 (36 Stat. 836), and subsection B of section 4 of the Act of December 5, 1924 (43 Stat. 702). The authorized purpose is irrigation.


Construction of Frenchtown Diversion Dam, Main Canal, and laterals was started in 1936. By 1937, the project was physically completed and the first water was available on May 18, 1937.

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Principal crops are hay, grain, and pasture. There are now very few full-time farms.

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Last updated: Apr 21, 2011