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Lewiston Orchards Project
Reservoir A Dam
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General Description| Plan| Development| Benefits

General Description

The Lewiston Orchards Project was originally constructed by private interests, beginning in 1906. Most of the project features have been rehabilitated or rebuilt by the Bureau of Reclamation. The project facilities include four diversion structures (Webb Creek, Sweetwater, West Fork, and Captain John), feeder canals, three small storage reservoirs (Soldiers Meadow, Reservoir A, and Lake Waha) a domestic water system including a water filtration plant which is no longer in use, and a system for distribution of irrigation water. The domestic water supply which initially was provided by surface water resources now comes entirely from groundwater resources developed by the Lewiston Orchards Irrigation District. A full irrigation water supply is delivered to project lands totaling over 3,900 acres, and a dependable domestic water system is now provided for some 16,000 residents.

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Soldiers Meadow Reservoir stores water from Webb Creek and from upper Captain John Creek via the Captain John Feeder Canal. This water is released, when needed, and diverted into Sweetwater Creek by the Webb Creek Diversion Dam and Webb Creek Canal. Water from the West Fork of Sweetwater Creek is stored in the offstream Lake Waha, which is fed by Lake Waha Feeder Canal. The stored water is pumped from Lake Waha back into the creek during the irrigation season. Sweetwater Diversion Dam diverts the releases into Sweetwater Canal, which empties into Reservoir A. Water for irrigation use is taken from Reservoir A by pipeline. Water for domestic use which had previously been a surface water supply is now provided from three deep wells developed by the Lewiston Orchards Irrigation District.

Facility Descriptions

Reservoir A and Lake Waha

Reservoir A is an offstream reservoir about 7 miles southeast of Lewiston, Idaho, that has a total capacity of 3,000 acre-feet (active 3,000 acre-feet). Safety of Dams work was completed at Reservoir A in 1999. A stability berm with drainage features was constructed along the downstream toe of the lower embankment, the upstream face of the lower embankment was reworked, and minor modifications were made on the upstream face of the upper embankment and to the outlet portal. In addition, the reservoir operating elevation was restricted to elevation 1800 feet reducing the reservoir's total capacity from 3,000 acre-feet to 1,960 acre-feet. This work was accomplished under the Bureau of Reclamation's Safety of Dams Program. An Issue of Elevation was completed in 2009, which indicated that the reservoir restriction could ease to allow storage to elevation 1804.0 feet, 2,440 acre-feet.

Lake Waha, a natural lake, also serves as an offstream reservoir. This lake is about 1 mile southwest of the village of Waha and has a capacity of 6,900 acre-feet.

Soldier's Meadow

The Soldiers Meadow Reservoir is located on Webb Creek about 6 miles southeast of Waha and has a total storage capacity of 2,370 acre-feet (active 2,370 acre-feet). In 1986, the top 25 feet of embankment at Soldiers Meadow Reservoir was replaced and the crest raised by 7 feet. In addition, filters were incorporated into the rebuilt embankment and the spillway and outlet works were modified. This work was accomplished under Reclamation's Safety of Dams Program.

Diversion Dams

Webb Creek Diversion Dam is on Webb Creek about 15 miles southeast of Lewiston, Idaho. It's a rockfill overflow weir type structure with a structural height of 20 feet. The diversion capacity is about 20 cubic feet per second.

Sweetwater Diversion Dam is on Sweetwater Creek about 12 miles southeast of Lewiston, Idaho. It is also of the rockfill overflow weir type, with a structural height of 12 feet.

The West Fork Diversion Dam is on the West Fork of Sweetwater Creek about 23 miles southeast of Lewiston, Idaho. It is a concrete overflow weir type structure which diverts water into the Lake Waha Feeder Canal for storage in Lake Waha. A pumping plant located on a floating platform at the north end of Lake Waha pumps the stored water back into the creek during the irrigation season for use by the irrigation district.

The Captain John Diversion consists of a small catch basin on Captain John Creek with the headworks structure diverting water into the Captain John Feeder Canal.

Domestic Water System

The water filtration plant is about 1 mile west of Reservoir A. The plant, as originally constructed, had a capacity of 1.5 million gallons per day. In 1977-1978, the district, primarily through work done by its own forces, increased the capacity to 2.3 million gallons per day by installing a rapid flow sand filter system. The filtration plant has not been used since 1985, because of the conversion of the domestic water system from a surface to a groundwater supply. A 1.5-million-gallon, ground-level concrete domestic storage reservoir is located at the treatment plant as well as an elevated steel storage tank. These facilities are still being used.

Initially, the distribution system had 58 miles of domestic pipe ranging from 0.75 to 14 inches in diameter. Forty-seven of these miles were constructed by the Bureau of Reclamation and 11 miles of extensions were installed later by the district. With continued urbanization of the area, there is now about 90 miles of domestic pipe. The 8- to 14-inch supply mains are asbestos-cement, the 4- and 6-inch distribution lines are either asbestos-cement or PVC, and all the lines from 0.75 to 3 inches are galvanized pipe.

In 1978, the district, with funds granted by the Economic Development Administration, drilled a 1,520-foot well within the project area to provide added capacity to the domestic system. The well is equipped with a 300-horsepower pump that pumps 600 gallons per minute. The well capability is 1,000 gallons per minute. The well is connected to the domestic distribution system by 6,200 feet of 8-inch-PVC pipe.

In 1985, a well was drilled at the water filtration plant. This well is 1,950 feet deep and is equipped with a 300-horsepower motor with a designed capacity of 900 gallons per minute. The well is connected to the 1.5 million gallon domestic reservoir with an 8-inch, 300 foot pipeline.

A third well was completed in 1998 to meet increasing domestic demands. This well is 2,630 feet deep. Total output is about 1,275 gallons per minute which is discharged into a new 2.5 million gallon storage reservoir.

The district`s domestic water system is intertied to the city of Lewiston. This provides for an interchange of domestic water supply when the need arises.

Irrigation Distribution System

The irrigation distribution system comprises over 80 miles of irrigation pipe ranging from 1 to 36 inches in diameter. Several flumes, siphons, and feeder canals are also included in the system. The irrigation distribution system also supplies the water for the fire hydrants in the area.

Operating Agencies

The Lewiston Orchards Irrigation District operates the project.

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The project is located near the confluence of the Clearwater and Snake Rivers in Idaho. In early days, it was a natural hunting and fishing ground for Indians. Early settlers found the climate delightful, as the elevation at Lewiston is only 738 feet. These settlers made their living by dry farming, mining, and lumbering. In 1906, a private company initiated irrigation in the project area.


The initial irrigation system provided a timber flume and a canal to carry water from Sweetwater Creek to Reservoir A. From Reservoir A, water was distributed through a system of wood-stave pressure pipelines to project lands. The water supply was augmented in 1915, 1922, 1934, and 1939 by making new diversions and by increasing the storage capacity. However, the wood-stave pipe system had a limited economic life and when the pipes were 30 years old and the flume 20 years old, the water distribution system had become unreliable. System losses ranged from 12 to 85 percent from section to section with the result that pressures were inadequate for satisfactory delivery of domestic water to many homes. In addition, portions of farm units were left dry because of the inadequate water supply. In 1939, the Irrigation District, aided by the Works Projects Administration, launched a program for replacing the wooden flumes with concrete bench flumes. This program continued in 1940-1941 but was not completed. Following these years, extensive maintenance and repair were necessary to keep the Webb Creek diversion in operation as the timber-crib diversion dam was in dire need of replacement. Water delivered through the single-pipe system was unsafe for domestic use, which caused a number of residents in the area to transport drinking water from the city of Lewiston.

Studies carried on during the 1970s considered the possibility of additional facilities to develop firm domestic water supplies. Included in these studies were a pumping plant on the Clearwater River with a design capacity of 30 cubic feet per second to deliver water to Reservoir A, the relining of Sweetwater Canal to reduce losses and restore full capacity, and the addition of a 2 million gallon domestic water reservoir.


The Lewiston Orchards Project was found to be feasible by the Acting Secretary of the Interior on May 31, 1946, pursuant to the Reclamation Project Act of August 4, 1939 (53 Stat. 1187, Public Law 76-260). However, before the Secretary'sreport was submitted to the Congress, the Act of July 31, 1946 (60 Stat. 717, Public Law 79-569) specifically authorized construction of the project. The authorized project purposes are irrigation and municipal and industrial water supply.


Following a full investigation by the Bureau of Reclamation and authorization by the Congress, construction and rehabilitation was started on September 15, 1947. All construction was completed on March 15, 1951.

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When originally developed, the project area consisted primarily of fruit orchards. Residential subdivision has since increased to the point where a significant portion of them are ownerships of less than two acres. Subdividing is expected to continue. At present, hay, grain, pasture, potatoes, and some fruits are the principal crops within the irrigated areas.

Domestic Water Supply

A domestic water supply is now furnished for a population of over 14,700. The demand for domestic water continues to increase as the area is developed into suburban residences.

Endangered Species

The Pacific Northwest Region consults with the NOAA Fisheries and the US Fish and Wildlife Service to ensure that project operations and other activities do not jeopardize ESA-listed species or their critical habitats. In 2010 the National Marine Fisheries Service (NMFS) provided a Biological Opinion on Reclamation's Operations and Maintenance of the Lewiston Orchards Project.

If conditions don't change this Opinion should be valid through 2020.

For more information on ESA related activites please go to:

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Last updated: Oct 24, 2012