Lost Lake Reservoir Report

Last Updated: December 4, 2025

Lost Lake, located in Larimer County, Colorado, is a state-regulated fish and wildlife pond with a primary purpose of serving as a habitat for aquatic life.


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Summary

Built in 1929, this Earth dam stands at a height of 15 feet and has a storage capacity of 359 acre-feet. With a surface area of 24 acres and a drainage area of 0, Lost Lake is fed by the Joe Wright Creek and has a maximum discharge capacity of 387 cubic feet per second.

Despite being classified with a low hazard potential and fair condition assessment, Lost Lake poses a high risk due to its location and the surrounding landscape. The dam has not been modified in recent years and was last inspected in 2006, with an inspection frequency of every 6 years. The spillway type is listed as "None," with a spillway width of 10 feet. While the emergency action plan status and risk management measures are not specified, Lost Lake remains a vital resource for fish and wildlife in the area.

Lost Lake, owned by the state of Colorado, is situated in Fort Collins and falls under the jurisdiction of the Colorado Division of Water Resources. With its serene location and vital role in supporting aquatic life, this Earth dam serves as a significant water resource in the region. For water resource and climate enthusiasts, Lost Lake offers a fascinating glimpse into the management and regulation of a crucial fish and wildlife habitat within the state of Colorado.

Year Completed

1929

Dam Length

630

Dam Height

15

River Or Stream

JOE WRIGHT CR-TR

Primary Dam Type

Earth

Surface Area

24

Hydraulic Height

15

Nid Storage

359

Structural Height

15

Hazard Potential

Low

Nid Height

15
       
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.