Willow Creek Dam (Oregon)
| Willow Creek Dam | |
|---|---|
Willow Creek Dam and Willow Creek Lake
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| Location | Morrow County, Oregon, U.S. |
| Coordinates | 45°20′49″N 119°32′41″W / 45.34695°N 119.54463°WCoordinates: 45°20′49″N 119°32′41″W / 45.34695°N 119.54463°W |
| Construction began | 1979 |
| Opening date | 1983 |
| Construction cost | $37,231,332 (as of June 18, 1997) |
| Operator(s) | U.S. Army Corps of Engineers |
| Dam and spillways | |
| Impounds | Willow Creek |
| Height | 160 feet (49 m) |
| Reservoir | |
| Creates | Willow Creek Lake |
| Total capacity | gross 13,250 acre feet (16,340,000 m3) usable 9,765 acre feet (12,045,000 m3) |
| Catchment area | 96 square miles (250 km2) |
| Surface area | 126 acres (51 ha) max 95 acres (38 ha) min |
Willow Creek Dam is a dam in Morrow County of the U.S. state of Oregon, located just east of Heppner's city limits. It was the first major dam in the United States constructed of roller-compacted concrete.
The dam's drainage basin is 96 square miles (250 km2) of arid rolling hills in the lower basin but with headwaters in the northern Umatilla National Forest. The dam's original purpose was primarily to store water for flood control, but also to serve recreation, fish and wildlife, and irrigation uses. The dam impounds Willow Creek to create Willow Creek Lake.
The lake level can be a maximum of 2,113.5 feet (644.2 m) elevation and a minimum of 2,063.0 feet (628.8 m) for a total usable storage capacity of 9,765 acre feet (12,045,000 m3).
A major flood killed approximately one quarter of Heppner's population in 1903—about 250 people. The flooding creek flow was 36,000 cubic feet per second (1,000 m3/s) as a result of a flash flood caused by thunderstorms, known as the Heppner Flood of 1903.
A flood control study was completed in 1962 at a total cost of $219. In 1965, a flood control project was authorized by U.S. Congress.
In 1979, the purpose of a dam project was changed to defer irrigation development for the future and eliminate water supply and water quality control.
Construction feasibility tests in 1972 placed a few layers of roller-compacted concrete. A 1:36 model (one inch equals three feet) was built and studied to determine downstream flooding and pool siltation characteristics as affected by the dam's spillway.
The dam was constructed by the Army Corps of Engineers between November 1981 and February 1983. Construction completed nearly on schedule, despite the workers initially being unfamiliar with the materials, processing, and techniques. It came in less than its budget of $50 million at $35 million. The dam's construction validated economic and construction speed benefits where 330,000 cubic meters (430,000 cu yd) of concrete were finished in less than five months at about $17 per cubic meter ($13/yd3), which includes additional efforts to correct defects.
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