Unity Dam

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
RegionFacilities in Pacific Northwest | Pacific Northwest Home Page
StateOregon
CountyBaker
ProjectBurnt River
Dam TypeZoned Earthfill
ReservoirUnity
WatercourseBurnt River
Location7 miles east of Hereford, Oregon
Longitude-118.1806
Latitude44.5042
Original Construction1936-1938
Modified Construction
National ID NumberOR00593
Hydrologic Unit Code

Dimensions
Structural Height82.0 ft
Hydraulic Height (Normal Operating Depth at Dam)58.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation3804.0 ft
Crest Elevation3827.3 ft
Crest Length694.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis3762.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)3820.0 ft
Top of Active Conservation Pool (Elevation)3820.0 ft
Top of Inactive Conservation Pool (Elevation)NA
Top of Dead Storage Pool (Elevation)3776.5 ft

Hydraulics & Hydrology
Total Water Storage at Elevation25,500 ac-ft at 3820.0 ft
Maximum Water Surface Elevation
Normal Water Surface Elevation3820.0 ft
Spillway TypeA concrete chute at the right abutment controlled by two 24-foot-wide by 16-foot-high radial gates
Auxiliary SpillwayNo
Spillway Capacity at Elevation10,000 cfs at 3820.0 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation620 cfs at 3820.0 ft
Diversion Capacity at Elevation
Drainage Area309.0 sq mi
Hydrometeorological Report (HMR)HMR 57
Probable Maximum Flood (PMF) Report

Contact Information
Owner
TitleArea Office Manager
OrganizationSnake River Area Office
Address230 Collins Road
CityBoise, ID 83702-4520
Phone (Fax)208 383-2275
Phone (Office)208 383-2248
Operator
OrganizationBurnt River Irrigation District
Address19498 Hwy 245
CityHereford, OR 97837
Phone (Office)541 446-3313


Last updated: Jul 26, 2012