Lost Lake #1 Reservoir Report

Last Updated: December 5, 2025

Lost Lake #1, also known as Lower Lost Lake, is a private water resource located in Hinsdale, Colorado, specifically in the city of South Fork.


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Summary

Built in 1907 for irrigation purposes, this earth dam stands at a height of 22 feet and stretches 182 feet in length. With a storage capacity of 1181 acre-feet, this reservoir serves multiple functions, including fish and wildlife pond, irrigation, and recreation.

Situated on Lost Lake Creek, this dam is regulated by the Colorado Department of Water Resources and is inspected regularly to ensure its structural integrity. With a low hazard potential and satisfactory condition assessment, Lost Lake #1 poses minimal risk to the surrounding area. The spillway, outlet gates, and overall design of the dam contribute to its efficient operation, maintaining a moderate risk assessment rating.

Water resource and climate enthusiasts will appreciate the historical significance and multi-purpose functionality of Lost Lake #1. From its construction over a century ago to its current role in sustaining irrigation and recreational activities, this dam on Lost Lake Creek embodies the balance between human utilization of water resources and environmental conservation. With careful regulation and maintenance, Lost Lake #1 continues to serve as a vital component of Colorado's water infrastructure.

Year Completed

1907

Dam Length

182

Dam Height

22

River Or Stream

LOST LAKE CREEK

Primary Dam Type

Earth

Surface Area

65

Hydraulic Height

19

Drainage Area

1

Nid Storage

1181

Structural Height

22

Outlet Gates

Slide (sluice gate) - 1

Hazard Potential

Low

Nid Height

22
       
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.