Ralston #1 Reservoir Report

Last Updated: December 5, 2025

Ralston #1 is a privately owned earth dam located in Garfield County, Colorado, near the city of Glenwood Springs.


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Summary

Built in 1904 for irrigation purposes, the dam stands at a height of 20 feet and has a storage capacity of 70 acre-feet. It is situated on West Coulter Creek-TR and is regulated by the Colorado Department of Water Resources.

Despite its low hazard potential, the dam is currently in unsatisfactory condition, as indicated by a recent inspection in June 2020. The spillway type is uncontrolled, with a width of 5 feet. The dam has one slide (sluice gate) outlet gate and a moderate risk assessment rating of 3. While there have been no major modifications to the structure in recent years, regular inspections are conducted every 6 years to assess its safety and integrity.

Water resource and climate enthusiasts interested in the historical significance and engineering aspects of Ralston #1 will find this dam a fascinating example of early irrigation infrastructure in the region. With its stone core and rock and soil foundations, the dam serves multiple purposes including fire protection, stock watering, and small fish pond management. Its location in a picturesque setting near Glenwood Springs adds to its appeal for those interested in exploring the intersection of water management and environmental conservation in Colorado.

Year Completed

1904

Dam Length

200

Dam Height

20

River Or Stream

WEST COULTER CREEK-TR

Primary Dam Type

Earth

Surface Area

5

Hydraulic Height

20

Nid Storage

70

Structural Height

20

Outlet Gates

Slide (sluice gate) - 1

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

20
       
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.