Overview
Unity Dam, located about 40 miles southwest of Baker, Oregon, is a rolled, zoned earthfill-type structure, 82 feet high above its foundation. The dam contains 254,000 cubic yards of earth and rock. The original total capacity (1938) was reported at 27,000 acre-feet. A 1991 sedimentation survey estimated the total capacity at 25,502 acre-feet (active 24,970 acre-feet).
Geology
The reservoir basin is a portion of a large depression lying between the Elkhorn Range on the north, the Blue Mountains to the west and the Ironsides Mountains on the south. Uplift of the surrounding ranges resulted in the deformation of existing formations, chiefly lava, and was accompanied by faulting on a moderate scale.
General
| Project | Burnt River |
| Location | 7 miles east of Hereford, Oregon |
| Longitude | -118.1806 |
| Watercourse | Burnt River |
| Reservoir | Unity |
| Original Construction | 1936-1938 |
| National ID Number | OR00593 |
| Dam Type | Zoned Earthfill |
| Latitude | 44.5042 |
Dimensions
| Crest Elevation | 3827.3 ft |
| Hydraulic Height (Normal Operating Depth at Dam) | 58.0 ft |
| Crest Length | 694.0 ft |
| Top of Joint Use Pool (Elevation) | 3820.0 ft |
| Top of Active Conservation Pool (Elevation) | 3820.0 ft |
| Top of Dead Storage Pool (Elevation) | 3776.5 ft |
| Streambed at Dam Axis | 3762.0 ft |
| Structural Height | 82.0 ft |
| Top of Inactive Conservation Pool (Elevation) | NA |
| Spillway Crest Elevation | 3804.0 ft |
Hydraulics & Hydrology
| Normal Water Surface Elevation | 3820.0 ft |
| Spillway Type | A concrete chute at the right abutment controlled by two 24-foot-wide by 16-foot-high radial gates |
| Auxiliary Spillway | No |
| Total Water Storage at Elevation | 25,500 ac-ft at 3820.0 ft |
| Outlet Works Capacity at Elevation | 620 cfs at 3820.0 ft |
| Drainage Area | 309.0 sq mi |
| Hydrometeorological Report (HMR) | HMR 57 |
| Spillway Capacity at Elevation | 10,000 cfs at 3820.0 ft |
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