Moon Lake Dam

Moon Lake Dam is a zoned earthfill, rockfaced dam built just downstream from a naturally occurring lake known as Moon Lake. The original lake has an estimated capacity of 13,900 acrefeet. The dam has a structural height of 98 feet and a volume of 513,000 cubic yards. Moon Lake Reservoir, on the West Fork of the Lake Fork of the Duchesne River, has a total capacity of 35,800 acre feet. The combined total of the original lake plus constructed storage is 49,500 acre feet. The surface area of the lake is 770 acres at 8137 feet elevation. Construction of Moon Lake Dam started in 1935 and finished in 1938. Curb and parapet were added in 1940 and finished in 1941.


Moon Lake Project lies partly on the south flank of the Unita Mountain Range and partly on the north limb of the Unita Basin in northeastern Utah.  The Unitas are the southeastern range of the central Rocky Mountains while the Unita Basin is the northern feature of the Colorado Plateau province.  The Unita Mountains are a highly eroded, east-west trending anticline whose crest has been raised by a series of block faults.  The core of the range is composed of Precambrian rock that has been exposed by deep erosion.  The Unita Basin is a very deep structural trough that has been filled with Tertiary and Recent age sediments.  There is perhaps as much as 30,000 feet of displacement between the elevation of a bed in the crest of the range and on the axis of the basin.

RegionFacilities in Upper Colorado | Upper Colorado Home Page
ProjectMoon Lake
Dam TypeZoned Earthfill, Rock-faced
ReservoirMoon Lake
WatercourseLake Fork River
LocationUinta Mountains
Original Construction1935-1938
Modified Construction
National ID NumberUT10128
Hydrologic Unit Code

Structural Height101 ft
Hydraulic Height (Normal Operating Depth at Dam)79 ft
Top Parapet (Elevation)
Spillway Crest Elevation
Crest Elevation8145 ft
Crest Length1108 ft
Crest Width
Base Width
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)8137.0 ft
Top of Inactive Conservation Pool (Elevation)8072.0 ft
Top of Dead Storage Pool (Elevation)8072.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation8137.0 ft
Normal Water Surface Elevation
Spillway Type
Auxiliary SpillwayNo
Spillway Capacity at Elevation10000.0 cfs at 8137.0 ft
Auxiliary Spillway Capacity at Elevation0.0 cfs at 0.0 ft
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation610.0 cfs at 8137.0 ft
Diversion Capacity at Elevation
Drainage Area110.0 sq mi
Hydrometeorological Report (HMR)
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationProvo Area Office
Address302 East 1860 South
CityProvo, UT 84606-7317
Phone (Office)801 379-1101
OrganizationMoon Lake Water Users Association
AddressPO Box 235
CityRoosevelt, UT 84066
Phone (Fax)435 722-2241
Phone (Office)435 722-2002

Last updated: Jun 23, 2009