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 No. 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.
National ID Number
Hydraulic Height (Normal Operating Depth at Dam)
Top of Active Conservation Pool (Elevation)
Top of Inactive Conservation Pool (Elevation)
Top of Dead Storage Pool (Elevation)
Streambed at Dam Axis
Hydraulics & Hydrology
Outlet Works Capacity at Elevation
1200 cfs at 5763.0 ft
3.7 sq mi
Hydrometeorological Report (HMR)
Normal Water Surface Elevation
Title: Area Office Manager Organization: Eastern Colorado Area Office Address: 11056 W. County Rd 18E City: Loveland, CO 80537-9711 Fax: 970-663-3212 Phone: 970-461-5410
Organization: Northern Colorado Water Conservancy District Address: 220 Water Ave. City: Berthoud, CO 80513 Phone: 800-369-7246
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