Allen Basin Reservoir Report

Last Updated: December 5, 2025

Allen Basin, located in Rio Blanco, Colorado, is a private irrigation dam completed in 1956 on the Middle Hunt Creek.


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Summary

This significant earth dam stands at a height of 52 feet and has a hydraulic height of 58 feet, with a storage capacity of 2808 acre-feet. The dam serves the primary purpose of irrigation, with a normal storage capacity of 2250 acre-feet and a drainage area of 3 square miles.

With a spillway type of "Uncontrolled" and a spillway width of 25 feet, Allen Basin has a significant hazard potential and is rated in fair condition as of the last assessment in September 2020. The dam has a moderate risk assessment score of 3 and is subject to regular inspections by the Colorado Division of Water Resources. The surrounding area covers 93 acres with a maximum discharge capacity of 1362 cubic feet per second.

For water resource and climate enthusiasts, Allen Basin offers a glimpse into the intricate network of private irrigation infrastructure in Colorado. With its historical significance and ongoing regulatory oversight, this dam serves as a vital component of water management in the region, highlighting the delicate balance between human intervention and natural resources in sustaining agricultural activities.

Year Completed

1956

Dam Length

690

Dam Height

52

River Or Stream

MIDDLE HUNT CREEK

Primary Dam Type

Earth

Surface Area

93

Hydraulic Height

58

Drainage Area

3

Nid Storage

2808

Structural Height

58

Hazard Potential

Significant

Nid Height

58
       
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.