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Spokane Valley Project
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General Description| Plan| Development| Benefits

General Description

The Spokane Valley Project provides an irrigation and domestic water supply for lands lying east of the city of Spokane, extending eastward to the Washington-Idaho boundary and on into Idaho for a short distance. The diversion dam on the Spokane River and the canal system previously used were abandoned in 1967 favor of a pumping system from wells into a pressure pipeline system that now provides sprinkler irrigation and serves domestic, municipal, and industrial requirements.

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Plan

The Spokane Valley is a 57 square mile lowland plain lying along both sides of the Spokane River. The valley is 6.5 miles wide at the Washington-Idaho boundary and narrows to 2.5 miles at the edge of Spokane. Bureau of Reclamation-built project facilities are designed to serve over 7,000 acres of irrigable land within the valley. The project was initially divided into six pressure zones or service areas: Carder, Corbin, Greenacres, West Farms, Otis Orchards, and East Farms but a series of interconnections now provide for `cross feeding`. Project water is pumped from ground water into elevated steel-tank regulating reservoirs and distributed under pressure through an asbestos-cement pipe system for irrigation and domestic, municipal, and industrial purposes. The system of wells, pumping units, and distribution facilities has an adequate capacity for present and future requirements. The main trunk pipe system for each area is used for irrigation and as a source of supply for domestic water. Irrigation service connections to ownerships existing at the time of construction were provided as a part of the project cost. Power for project pumping is obtained from the Federal Columbia River Power System.

The water supply is obtained by pumping from deep wells that are 16 to 22 inches in diameter, and 90 to 150 feet deep. The wells are located at 11 different sites in clusters of 3 wells at 10 sites and 4 wells at 1 site. Water from the well is lifted to eleven 6,680 cubic-foot (50,000 gallon) elevated steel tanks at each site that range in height from 125 to 187 feet, and are used as equalizing reservoirs. Additional storage has been provided by the construction of two 2-million ground level steel reservoirs and two pre-cast concrete tanks, one of 110,000 gallon capacity and the other of 300,000 gallons. The wells are equipped with turbine pumps that range in capacity from 2.6 to 7.4 cubic feet per second, and motor sizes that range from 100 to 300 horsepower. Total dynamic head ranges from 241 to 309 feet at the 34 wells. The distribution system now includes 140 miles (expanded from an initial 104 miles) of buried asbestos cement pipelines ranging in diameter from 6 to 24 inches, complete with sectionalizing valves and service connection accessories. Two booster pump stations have been recently added by the irrigation district to the distribution system.

All water service is metered. Because of extensive urbanization of the area, the irrigation district has a program to install fire hydrants to meet fire safety needs.

Operating Agencies

The project has been operated and maintained by Consolidated Irrigation District No. 19 since January 1, 1968.

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Development

History

Settlement of the valley began about the turn of the century; irrigation developments date from about 1905. The growth of Spokane as a commercial and industrial center has led to subdivision of much of the irrigated land into homesites.

The Spokane Valley Land and Water Co., organized in 1903, irrigated about 22,000 acres of land. The company sold a block of its land in 1908 to finance construction of a canal system. By 1912, a canal along the north side of the river led from Post Falls, Idaho, to some of the lands. Seepage in the unlined canals, failure of wooden flumes and other structures, and the limited amount of water that could be diverted in August and September severely handicapped effective irrigated agriculture.

A new organization took over the water rights, irrigation facilities, and other assets in 1921, and two irrigation districts were formed in 1922. The South Branch Canal and lateral systems were built in 1923. In succeeding years additional irrigation districts were organized, the canal system was partially lined, and deteriorated wooden structures were replaced. Prior to the time the Bureau of Reclamation was requested to aid in construction, the distribution system was again in need of rehabilitation, and continued operation of gravity canals and laterals had become more difficult because of new residential subdivisions.

Investigations

In 1954, the Bureau of Reclamation published a reconnaissance report which outlined six alternative methods of rehabilitating the project. The seven irrigation districts concurred in selecting a plan to abandon the diversion dam and water conveyance systems and replace them by pumping from wells to be drilled at several points in the valley. The wells would serve the irrigated land through pressure pipeline systems.

This selection resulted in the publication of a feasibility report in August 1956 which detailed the chosen plan, computed benefits, and determined probable charges.

Authorization

The project was authorized by the Act of September 16, 1959 (73 Stat. 561, Public Law 86-276) for the purpose of providing irrigation water to 10,300 acres. The Act of September 5, 1962 (76 Stat. 431, Public Law 87-630) amended this act by reducing the irrigation area to approximately 7,250 acres and adding domestic, municipal and industrial uses as a project purpose.

Construction

Construction of project facilities began in 1963 and was completed in 1967.

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Benefits

Irrigation

Uniform irrigation supplies make possible a more reliable crop yield in an area where only about 6 inches of natural precipitation fall during the growing season. Hay, pasture, grain, and vegetables are the principal agricultural products.

Municipal and Industrial

Extensive benefits are realized through the development of an adequate water supply for domestic, municipal, and industrial use. Because of urban growth, domestic service demand is increasing constantly.

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Last updated: May 17, 2011