Carter Lake Dam


Three dams help form Carter Lake Reservoir. The Reservoir is one of two final storage locations for water diverted from Colorado's West Slope via the Colorado-Big Thompson Project. Water exits the reservoir through Dam #1 and the St. Vrain Supply Canal serving communities ranging from Longmont to Boulder and Fort Morgan, Colorado before water is returned to the South Platte River system.

Dam No. 1, the largest, occupies a gap across the Dakota sandstone hogback, and ifs founded on Morrison shale and limestone and the Sundance sandstone. The abutments are Dakota sandstone and shale, and all the strata have about 15 degree dip downstream.

The geology of Dam No. 2 is somewhat more complex. Due to sharp echelon folding, the hogback structure ends abruptly against a southward plunging anticline. The result is that the foundation strata dip to the southwest into the right abutment, with dips varying from 5 degrees on the right abutment to 70 degrees on the left abutment. The dam rests on upturned edges of the Morrison shale and limestone, Sundance sandstone and the Lykins formation.

Dam No. 3 rests entirely on Lyons sandstone.

RegionFacilities in Great Plains | Great Plains Home Page
ProjectColorado-Big Thompson
Dam Type
ReservoirCarter Lake
Watercourseoffstream Storage
Original Construction1950-1952
Modified Construction
National ID NumberCO01650
Hydrologic Unit Code

Structural Height214.0 ft
Hydraulic Height (Normal Operating Depth at Dam)190.0 ft
Top Parapet (Elevation)
Spillway Crest Elevation
Crest Elevation5769.0 ft
Crest Length1235.0 ft
Crest Width
Base Width
Volume of Dam Construction Materials
Streambed at Dam Axis5579.0 ft
Top of Exclusive Flood Control Pool (Elevation)
Top of Joint Use Pool (Elevation)
Top of Active Conservation Pool (Elevation)5759.0 ft
Top of Inactive Conservation Pool (Elevation)5640.0 ft
Top of Dead Storage Pool (Elevation)5618.0 ft

Hydraulics & Hydrology
Total Water Storage at Elevation
Maximum Water Surface Elevation
Normal Water Surface Elevation5759.0 ft
Spillway Type
Auxiliary SpillwayNo
Spillway Capacity at Elevation
Auxiliary Spillway Capacity at Elevation
Uncontrolled Spillway Capacity at Elevation
Outlet Works Capacity at Elevation1200 cfs at 5763.0 ft
Diversion Capacity at Elevation
Drainage Area3.7 sq mi
Hydrometeorological Report (HMR)HMR 55
Probable Maximum Flood (PMF) Report

Contact Information
TitleArea Office Manager
OrganizationEastern Colorado Area Office
Address11056 W. County Rd 18E
CityLoveland, CO 80537-9711
Phone (Fax)970 663-3212
Phone (Office)970 667-4410
OrganizationNorthern Colorado Water Conservancy District
AddressPO Box 679
CityLoveland, CO 80539
Phone (Office)970 667-2437

Last updated: Mar 29, 2013