Arthur R. Bowman Dam (formerly Prineville Dam) is an earthfill structure on the Crooked River about 20 miles upstream from Prineville. The dam has a height of 240 feet, crest length of 790 feet, and a volume of 1,424,000 cubic yards of material.
The spillway consists of an uncontrolled-crest inlet structure, chute, and stilling basin. Capacity of the spillway is 8,120 cubic feet per second at maximum water surface elevation of 3,257.9 ft. The outlet works has an intake structure with an 11-foot-diameter circular tunnel upstream from the gate chamber, an 11-foot modified horseshoe tunnel downstream from the gate chamber, and a stilling basin which is shared with the spillway. The capacity of the outlet works is 3,300 cubic feet per second at normal water surface elevation of 3,234.8 ft.
The total capacity of Prineville Reservoir at closure was 154,690 acre-feet (active 152,800 acre-feet). A reservoir sedimentation survey completed in 1998 estimates the total capacity at 150,200 acre-feet (active 148,600 acre-feet).
The Crooked River drains a mountainous area composed of volcanic tuff and agglomerate beds, and basalt, rhyolite and andesite lava flows ranging in age from early Eocene to Recent. The drainage basin exhibits a wide variety of topographic forms owing to variation in the resistance of volcanic beds and the varying degree of folding in the area. Depth of overburden at the damsite is not uniform. In the areas where bedrock exposures are common, overburden ranges from several feet deep.
|Dam Type||Zoned Earthfill|
|National ID Number||OR00579|
|Crest Elevation||3270.0 ft|
|Hydraulic Height (Normal Operating Depth at Dam)||182.0 ft|
|Crest Length||800.0 ft|
|Top of Joint Use Pool (Elevation)||3234.8 ft|
|Top of Active Conservation Pool (Elevation)||3234.8ft|
|Spillway Crest Elevation||3234.8 ft|
|Streambed at Dam Axis||3076.0 ft|
|Structural Height||240.0 ft|
|Top of Inactive Conservation Pool (Elevation)||3114.0 ft|
|Top of Dead Storage Pool (Elevation)||3112.0 ft|
Hydraulics & Hydrology
|Spillway Type||Ungated overflow|
|Spillway Capacity at Elevation||8,120 cfs at 3234.8 ft|
|Outlet Works Capacity at Elevation||3300 cfs at 3234.8 ft|
|Hydrometeorological Report (HMR)||HMR 57|
|Normal Water Surface Elevation||3234.8 ft|
|Total Water Storage at Elevation||152,800 ac-ft|
|Drainage Area||2635.0 sq mi|