Boysen Dam


Boysen Dam is a zoned earthfill structure having a structural height of 220 feet. An overflow, weir-type spillway controlled by radial gates is located on the right abutment and surcharges immediately upstream and left of the powerplant.

Design discharge through the spillway is 25,000 cubic feet per second at elevation 4725.00 The Boysen Reservoir has a total controlled storage capacity of 802,000 acre-feet at water surface elevation 4725.00

The outlet works is on the right abutment of the dam. Discharge is through a 66-inch-diameter steel pipe located above the power penstock and a 57-inch-diameter steel pipe joined to the 10-foot-diameter power penstock serving Unit 1 in the powerhouse.

The powerplant has an installed capacity of 15,000 kilowatts developed by two units operating under an average head of 99 feet. Each unit is served by a 10-foot-diameter steel penstock joined to a common 15-foot-diameter steel penstock immediately upstream from the powerplant. The 15-foot-diameter penstock leading from the intake structure to the units was located to utilize the bore of an existing railroad tunnel made available through relocation of the CB&Q railroad.

Other features of the construction activity were the relocation of 13.5 miles of the railroad track, which required a tunnel 1.25 miles long, seven bridges, two sidings, and other construction features.

Folded and faulted shales and sandstones lying over pre-Cambrian diorites, with up to 70 feet of alluvium in the riverbed.

RegionFacilities in Great Plains | Great Plains Home Page
ProjectBoysen Unit, Pick-Sloan Missouri River Basin Program
Dam Type
WatercourseWind River
LocationOn the Wind River approximately 17 miles south of Thermopolis, Wyoming.
Net Generation54,362,300 kWh
Original Construction1947-1952
Modified Construction
National ID NumberWY01299
Hydrologic Unit Code

Structural Height220.00 ft
Hydraulic Height (Normal Operating Depth at Dam)117.00 ft
Top Parapet (Elevation)
Spillway Crest Elevation4,700.00 ft
Crest Elevation4,758.00 ft
Crest Length1,143.00 ft
Crest Width30.00 ft
Base Width919.00 ft
Volume of Dam Construction Materials 1,527,386.00 cu yd
Streambed at Dam Axis
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)4,725.00 ft
Top of Active Conservation Pool (Elevation)4,717.00 ft
Top of Inactive Conservation Pool (Elevation)4,685.00 ft
Top of Dead Storage Pool (Elevation)4,657.00 ft

Hydraulics & Hydrology
Total Water Storage at Elevation952,400.00 acre-ft at 4,732.20 ft
Maximum Water Surface Elevation
Normal Water Surface Elevation
Spillway TypeConcrete lined chute in right abutment, controlled by two 30- by 25-ft radial gates.
Auxiliary Spillway
Spillway Capacity at Elevation25,000.00 cfs at 4,725.00 ft
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation1,300.00 cfs at 4,725.00 ft
Diversion Capacity at Elevation
Drainage Area
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report

Contact Information
TitleFacility Manager
OrganizationBig Horn Basin Field Office
Address#4 Reclamation Road
CityCody, WY 82414
Phone (Office)307-527-6256 (ext. 260)
TitleFacility Manager
OrganizationBig Horn Basin Field Office
Address#4 Reclamation Road
CityCody, WY 82414
Phone (Office)307-527-6256 (ext. 260)

Last updated: Mar 29, 2013