Boise River Diversion Dam


The Boise River Diversion Dam, on the Boise River about 7 miles southeast of Boise, Idaho, is a rubble-concrete, weir-type structure with a hydraulic height of 39 feet. The dam diverts water into the New York Canal which serves distribution laterals and feeds Lake Lowell. A small canal known as the Penitentiary Canal, also originating at the diversion dam, distributes water on the north side of the Boise River to a small area of land east of Boise. The powerplant consists of three 500-kilowatt units that began operation in 1912. However, in 1983, the powerplant was placed in a "ready reserve" status due to the age of the generators and excessive maintenance costs. Due to the deteriorated condition of the equipment and high operating costs resulting from full-attended operation, the powerplant was placed in ready reserve status in 1982. The plant was reconstructed in 2002 to 2004 and returned to service in June, 2004. The nameplate rating for the plant was increased from the original 1500 kW to 3300 kW. The existing double turbine configuration was retained, but refurbished with new materials and technology. New modern generators were installed inside the original generator housings.  

RegionFacilities in Pacific Northwest | Pacific Northwest Home Page
Dam Type Concrete and masonry weir
Reservoir Boise Diversion Pool
WatercourseBoise River
Location7 miles SE of Boise, ID
Net Generation9,429,000 kWh in 2011
Original Construction1906-1908
Modified Construction
Hydrologic Unit Code
National ID NumberID00281

Structural Height 68.0 ft
Hydraulic Height (Normal Operating Depth at Dam) 39.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation 2812.84 ft
Crest Elevation 2829.84 ft
Crest Length500 ft
Crest Width 12 ft
Base Width 100 ft
Volume of Dam Construction Materials
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)

Hydraulics & Hydrology
Total Water Storage at Elevation 0 active; 1,200 ac-ft total at 2817.0 ft
Maximum Water Surface Elevation
Normal Water Surface Elevation
Spillway Type Overflow with flashboards
Auxiliary Spillway
Spillway Capacity at Elevation 37,700 cfs at 2827.84 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation 1,700 cfs at 2817.0 ft
Diversion Capacity at Elevation 2,800 cfs New York Canal
Drainage Area
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationSnake River Area Office
Address230 Collins Road
CityBoise, ID 83702-4520
Phone (Fax)208 383-2275
Phone (Office)208 383-2248
OrganizationBoise Project Board of Control
Address2465 Overland Road
CityBoise, ID 83705-3155
Phone (Office)208 344-1141

Last updated: May 04, 2012