Lucky Peak Dam and Lake

Lucky Peak 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.

Since completion of the dam in the mid 1950’s, Lucky Peak Lake has offered a variety of recreational and natural resource benefits.

Located just 15 minutes from Boise’s greater urban area, Lucky Peak Lake experiences great and diverse pressures from a broad spectrum of visitors. Managing nearly 8,000 acres of public lands and waters in a manner that promotes multiple and diverse uses while minimizing conflicts is a privilege and a challenge our team gratefully accepts and continuously works to improve. As host to nearly one million visits each year, Lucky Peak Lake can’t be everything to everyone, but looking at its potential in a regional context, mindful of our strengths and resource limitations, we strive to deliver certain opportunities with excellence.

Project Information

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

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

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

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