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Arnold Project

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Arnold Project History (25 KB) (pdf)
General Description| Plan| Development| Benefits

General Description

The Arnold Project, a private development southeast of Bend, Oregon, diverts water from the Deschutes River a short distance above Lava Island Falls for approximately 4,300 acres of irrigable land. Project features include Arnold Diversion Dam, Arnold Flume and Canal, and laterals.

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Water is diverted from the Deschutes River by Arnold Diversion Dam, and is carried through the Arnold Flume and Canal in an eastward direction. Final delivery to the project lands is made through the lateral system. Storage is provided in Crane Prairie Reservoir.

Facility Descriptions

Arnold Diversion Dam is of the wing type, extending a short distance into the river from the east bank. The main structure of the distribution system is the 1-mile-long Arnold Flume. The original flume was made of wood, but was replaced with a semicircular steel flume and new concrete headworks by the Bureau of Reclamation. Two shorter wood-built flumes, the Suttong and 0`Donnell, also were replaced. The Suttong Flume was replaced by 710 feet of pretensioned concrete pipe, and the O`Donnell Flume was replaced with a steel pipeline 265 feet long. The main Arnold Canal was originally 17 miles long, but since rehabilitation it has been reduced in length to about 11 miles. The canal has a capacity of 120 cubic feet per second at the diversion. A lateral system serves the project lands.
Operating Agencies

The project is operated and maintained by the Arnold Irrigation District. In 1991, the irrigation district completed repayment of its construction obligation to the United States. Pursuant to contract provisions and mutual agreement of the parties, all contractual arrangements between the United States and the district were terminated in 1995. The district's 1938 agreement with Central Oregon Irrigation District regarding the use of water from Crane Prairie Reservoir remains in effect.

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Irrigation in the Deschutes River Basin dates back to 1871 when individual farmers diverted water from Squaw Creek, a tributary of the Deschutes River. In 1895, construction of the Squaw Creek Canal was begun and, by 1905, the area had been developed by private interests to include the Swalley Canal, the Central Oregon Irrigation District canals, and the Arnold Canal.

The Arnold Irrigation Co. was organized in 1905, and by 1920 had consolidated with three other small irrigation companies, the Pine Forest Ditch Company, the Bend Company, and the North Irrigation Company. Since 1936, the group has been organized as the Arnold Irrigation District.


In 1934-1935, the Bureau of Reclamation made a comprehensive study of all storage possibilities above the Crooked River, and published the results in the report upon which the Deschutes Project authorization was based. Meanwhile, local interests constructed a rockfilled timber crib dam at the Crane Prairie site and a diversion dam in the vicinity of Bend. The Crane Prairie Dam was later rebuilt by the Bureau of Reclamation as part of the Deschutes Project and now furnishes storage for the Arnold Project and for some units in the Deschutes Project. As most of the structures in the Arnold distribution system were built of wood, replacement became necessary. By 1948, the largest flume on the main canal just below the intake was in danger of failure, threatening serious loss to irrigated crops throughout the entire district. The irrigation district asked the Bureau of Reclamation to help rehabilitate this flume.


The Deschutes Project, which included a supplemental water supply in Crane Prairie Reservoir for the Arnold Irrigation District, was authorized by a finding of feasibility by the Secretary of the Interior on September 24, 1937, and approved by the President on November 1, 1937, 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 rehabilitation of the Arnold Project distribution works was authorized on July 25, 1947 by the Interior Department Appropriation Act, 1948 (61 Stat. 460, 473, Public Law 80-247). The authorized purpose of the Arnold Project is irrigation.


The Bureau of Reclamation replaced the old wood flume with a semicircular steel flume and installed new concrete headworks. This work was started in 1948 and completed in 1949. Repairs to the diversion dam were completed in 1951. Replacement of the Suttong Flume and rehabilitation of the O`Donnell Flume and Siphon were completed in 1962.

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The project produces grain, alfalfa, grass hay, and pasture as the principal crops.

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Last updated: Jan 11, 2012