Walla Walla District

Authorization
The project was authorized by the Flood Control Act of 1946.

Progress
Construction of Lucky Peak Dam began in 1949. It was dedicated June 23, 1955.

 

Project
The project includes the dam, Lucky Peak Lake, federally owned lands managed by the Corps, and operational and recreational facilities. The project provides flood control, fish and wildlife habitat, irrigation and recreation. Since 1961, more than $2.37 billion in potential flood damages have been prevented.

 

Lucky Peak Dam
The dam is a rolled earthfill dam about 250 feet above the streambed and 1,700 feet long at the crest. The spillway, located on the left abutment, has a 600 foot long, free-overflow concrete ogee crest. The outlet works, located in the left abutment, consist of a 23 foot diameter tunnel with six slide gates and one hollow jet valve. There are two 10 foot by 23 foot Broome-type emergency gates located in the intake tower.

 

Reservoir
Upstream of Lucky Peak Dam is a storage reservoir, Lucky Peak Lake. The lake, at normal full pool, elevation 3,055 feet Mean Sea Level (MSL), is 12 miles long. It has 45 miles of shoreline and 3,019 acres of surface area. The reservoir provides a total storage capacity of 306,000 acre-feet at pool elevation 3,060 feet MSL.

 

Generators
A license to construct and operate power facilities at the dam was issued by the Federal Energy Regulatory Commission to the Boise Project Board of Control, a non-federal interest, on June 10, 1980. The powerhouse facility includes a visitor center, reconstruction of the outlet and construction of a second outlet, and the mitigation and enhancement of recreation and operation facilities. The power-production project was dedicated on Oct. 7, 1988. Seattle City Light, under an agreement with the Boise Project Board of Control, operates and maintains the power facility. The three generators are capable of producing a total of 101.25 megawatts of electricity.

 

Lands
There are 4,288 acres of public lands surrounding Lucky Peak Lake. These include fee lands that are federally owned and managed by the Corps, as well as easement lands to which the Corps has specific rights or easements (i.e., flowage or access). There are 4,079 acres of Corps-managed lands that are used for public recreation, wildlife habitat and operation purposes. The state of Idaho operates Lucky Peak State Park at three locations on Lucky Peak Lake. Other recreation areas are operated by the Corps. The dam and its facilities lie within Idaho Department of Fish and Game’s Boise River Wildlife Management Area, the major game range in the state. The State of Idaho has developed wildlife habitat especially for mule deer on project lands. Corps recreation facilities at Lucky Peak Lake consist of 20 day-use areas, four boat launch ramps and three swimming areas. The fiscal year 2015 visitation to Lucky Peak Lake was more than 921,000.

 

People
Less than 10 full-time Walla Walla District employees work at Lucky Peak Dam and Lake. They serve as park rangers, natural resource specialists, administrative staff and maintenance workers. Temporary employees augment the staff during high-visitation months. Together, they manage the safe and continuous operation of the dam and its facilities. The staff also manages a volunteer program to help maintain and make improvements to Lucky Peak Lake’s numerous public recreation facilities.

 

Budget
During fiscal year 2015, total expenditures were about $2.2 million for the Lucky Peak Project.

Dam
Type – Rolled earth and gravel fill, impervious core
Top elevation – 3,078 ft/msl

Height
- Above foundation – 340 ft
- Above streambed – 256 ft
Crest length – 1,700 ft
Width at top – 30 ft

Spillway
Crest elevation – 3,060 ft/msl
Length – 600 ft
Design discharge – 93,300 cfs

Outlet Works
Type - Steel-lined pressure tunnel
Diameter of tunnel – 22 ft
Length of tunnel – 1,365 ft
Elevation of tunnel behind dam – 2,824 ft/msl

Discharge capacity
- At minimum lake level – 17,000 cfs
- At normal lake level – 30,000 cfs
Number and size of gates - Six - 5'3" x 10'0"
Gate operation - Hydraulic cylinders
Diameter of jet valve – 30 in

Lucky Peak Lake Data
Elevation of Lake
Flood storage – 3060 msl
Normal operating – 3055 msl
Minimum operating – 2905 msl
Empty (Boise River) – 2824 msl

Area of Lake (Acres)
Normal at El. 3055 – 3,019 (Reference 1)
Minimum at El. 2905 – 820

Length of
Shoreline at El. 3055 – 45 miles
Boise River – 12 miles
Mores Creek 45 – 5 ½ miles

Storage Capacity
Top 5 feet, El., 3055 to 3060 – 13,905 acre-ft
Active (usable), El. 2905 to 3055 – 264,371 acre-ft
Minimum, EL. 2824 to 2905 – 28,767 acre-ft
Total gross, El. 2824 to 3060 – 307,043 acre-ft

Water Allocation (Reference 2)
Contracted irrigation – 111,950 acre-ft
Streamflow maintenance – 152,300 acre-ft
Storage for recreation – 28,800 acre-ft

References
1See SD-8 for calculations.
2As shown in Idaho Department of Water Resources Permit No. 63-3618/R-1183.