Big Beaver Reservoir Report

Last Updated: December 5, 2025

Big Beaver is a privately owned earth dam located in Mesa, Colorado, near the city of Molina.


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Summary

Built in 1947 by designer Frank A. Matteson, this dam serves the primary purpose of irrigation for the surrounding area. With a height of 30 feet and a length of 180 feet, Big Beaver has a storage capacity of 175 acre-feet and a normal storage level of 128 acre-feet.

The dam, situated on Bull Creek-TR, has a significant hazard potential and is classified as having a fair condition assessment as of the last inspection in July 2020. It features an uncontrolled spillway, one slide (sluice gate) outlet gate, and a spillway width of 25 feet. Despite its moderate risk assessment rating, the dam has been deemed safe for operation with state regulation, inspection, and enforcement in place.

Water resource and climate enthusiasts will find Big Beaver an intriguing structure due to its historical significance, efficient irrigation function, and the engineering challenges associated with its design and maintenance. Its location in a picturesque setting in Colorado adds to the allure for those interested in exploring the intersection of human infrastructure and natural resources in the context of water management.

Year Completed

1947

Dam Length

180

Dam Height

30

River Or Stream

BULL CREEK-TR

Primary Dam Type

Earth

Surface Area

11

Hydraulic Height

30

Drainage Area

1

Nid Storage

175

Structural Height

37

Outlet Gates

Slide (sluice gate) - 1

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

37
       
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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.