Lucky Peak Dam

Lucky Peak Dam and Lake

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.

Project Information

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 Project Fact Sheet

 

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 U.S. Army Corps of Engineers (USACE), and operational and recreational facilities. The project provides flood risk management, 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 2,340 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. At normal full pool - elevation 3,055 feet above mean sea level (MSL) - the lake is 12 miles long, has 45 miles of shoreline, and 3,019 acres of surface area. The reservoir provides a total storage capacity of 264,400 acre-feet. Flood risk management and irrigation storage is jointly coordinated between USACE and the Bureau of Reclamation, which operates two upstream dams, Arrowrock Dam (opened in 1915) and Anderson Ranch Dam (opened in 1950). Together, this three-dam system stores approximately 1,000,000 acre-feet when full.

 

Hydropower

The Federal Power Act of 1920 authorized the use of federal lands by non-federal entities to construct hydropower facilities.  The Federal Energy Regulatory Commission issued a license to the Boise-Kuna Irrigation District to construct a 100-megawatt facility in June, 1980.  After reconstruction of the primary outlet and construction a new secondary outlet, the plant went online in 1988. The power purchaser, Seattle City Light, operates and maintains the facility.

 

Public Lands

There are 4,288 acres of public lands surrounding Lucky Peak Lake. These include lands that are federally owned and managed by USACE, as well as easement lands to which USACE has specific rights to flood.

There are 4,079 acres of USACE-managed lands that are used for public recreation, wildlife habitat and operations purposes. Lucky Peak Lake bisects Idaho Fish and Game’s Boise River Wildlife Management Area, a major winter range in the state for deer and elk. The Idaho State Parks operates Lucky Peak State Park Units at three locations on Lucky Peak Lake.  Ada County Parks and Waterways provides over 500 public-use floating dock sections. USACE recreation facilities at Lucky Peak Lake consist of seven park areas, four boat launch ramps, and 80 dispersed recreation sites accessible only by boat. The fiscal year 2020 public visitation to all areas was approximately 950,000 visits.

 

People

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 operate park areas and make improvements to Lucky Peak Lake’s numerous public recreation facilities.

 Project Pertinent Data
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.

Contact Us

Lucky Peak Dam and Lake
9723 E. Hwy 21
Boise, ID 83706-9302
Phone: 208-343-0671