Twin Lakes Reservoir Reservoir Report

Last Updated: December 4, 2025

Twin Lakes Reservoir, located in Larimer County, Colorado, is a vital water supply source owned by the local government and regulated by the Colorado Department of Water Resources.


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Summary

The reservoir, completed in 1998, has a storage capacity of 419 acre-feet and serves the primary purpose of water supply. With a significant hazard potential but a satisfactory condition assessment, the dam is designed as an earth type structure with stone core and rock foundation, standing at a height of 35 feet and a length of 245 feet.

Situated on the South Fork Cache La Poudre River, Twin Lakes Reservoir plays a crucial role in water management in the region, with a maximum discharge capacity of 3560 cubic feet per second. The spillway, of uncontrolled type with a width of 72 feet, aids in managing water levels during peak flow periods. The dam features a slide (sluice gate) outlet gate and is inspected biennially to ensure its safety and functionality.

As climate change impacts water resources, Twin Lakes Reservoir stands as a key infrastructure for water supply in Fort Collins, providing a moderate risk management measure with emergency action plans in place. With its strategic location and essential role in the local water system, this reservoir is a significant asset in sustaining water resources in the dynamic environmental conditions of Colorado.

Year Completed

1998

Dam Length

245

Dam Height

35

River Or Stream

S FORK CACHE LA POUDRE-TR

Primary Dam Type

Earth

Surface Area

25

Hydraulic Height

33

Nid Storage

419

Structural Height

41

Outlet Gates

Slide (sluice gate) - 1

Hazard Potential

Significant

Foundations

Rock

Nid Height

41
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
Fair
No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action. Note: Rare or extreme event is defined by the regulatory agency based on their minimum
Poor A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency. Investigations and studies are necessary.
Unsatisfactory
A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
Not Rated
The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Not Available
Dams for which the condition assessment is restricted to approved government users.

Hazard Potential Classification

High
Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
Significant
Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environment damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
Low
Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
Undetermined
Dams for which a downstream hazard potential has not been designated or is not provided.
Not Available
Dams for which the downstream hazard potential is restricted to approved government users.