Thurston Lake Reservoir Report

Last Updated: December 5, 2025

Thurston Lake, located in Lamar, Colorado, is a privately owned reservoir primarily used for recreation and irrigation purposes.


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Summary

Built in 1928, this earth dam structure stands at 20 feet high and spans 4000 feet in length, with a storage capacity of 4550 acre-feet. The lake covers 650 acres and is fed by the Arkansas River-OS, making it an important water resource in Prowers County.

The dam at Thurston Lake is regulated by the Colorado Division of Water Resources, with regular inspections ensuring its fair condition and significant hazard potential. In case of emergencies, the dam has an uncontrolled spillway with a width of 100 feet. The lake has a maximum discharge rate of 1560 cubic feet per second and a normal storage capacity of 1714 acre-feet, serving as a crucial water source for the surrounding area. Despite its age, Thurston Lake continues to play a vital role in water management and recreation activities in the region.

With its scenic surroundings and recreational opportunities, Thurston Lake offers a tranquil escape for water resource and climate enthusiasts. From boating and fishing to wildlife observation, this reservoir provides a diverse range of outdoor activities while also serving as a key irrigation source for the local community. As efforts continue to ensure the dam's safety and efficiency, Thurston Lake remains an essential part of Colorado's water infrastructure and a valuable asset for both residents and visitors alike.

Year Completed

1928

Dam Length

4000

Dam Height

16

River Or Stream

ARKANSAS RIVER-OS

Primary Dam Type

Earth

Surface Area

650

Hydraulic Height

16

Drainage Area

1

Nid Storage

4550

Structural Height

20

Outlet Gates

Slide (sluice gate) - 0

Hazard Potential

Significant

Nid Height

20
       
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.