Terry Lake Reservoir Report

Last Updated: December 5, 2025

Terry Lake in Larimer, Colorado, stands as a historic Earth dam completed in 1890 primarily for irrigation purposes.


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Summary

With a height of 38 feet and a storage capacity of 9,960 acre-feet, this reservoir on Dry Creek-Tr is a vital water resource in the region. The dam's spillway, uncontrolled in nature, has a width of 300 feet, making it a significant structure in managing water flow.

Despite being privately owned, Terry Lake is subject to state regulation, permitting, inspection, and enforcement by the Colorado Division of Water Resources. With a high hazard potential and satisfactory condition assessment, the dam poses moderate risk, prompting the need for effective risk management measures. The surrounding area boasts a surface area of 500 acres and a drainage area of 4 square miles, making it a crucial site for both irrigation and recreation activities. Enthusiasts of water resources and climate can appreciate the historical significance and functional importance of Terry Lake in the water management landscape of Colorado.

Year Completed

1890

Dam Length

6400

Dam Height

38

River Or Stream

DRY CREEK-TR

Primary Dam Type

Earth

Surface Area

500

Hydraulic Height

40

Drainage Area

4

Nid Storage

9960

Structural Height

40

Hazard Potential

High

Nid Height

40
       
Seasonal Comparison

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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.