Dunnagan Reservoir Report

Last Updated: December 5, 2025

Dunnagan is a privately owned irrigation dam located in Colorado, specifically in Archuleta County near Blanco, NM.


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Summary

Built in 1949 by the USDA NRCS, this earth dam stands at a height of 19 feet and has a length of 569 feet, with a storage capacity of 201 acre-feet. The primary purpose of Dunnagan is irrigation, serving the surrounding area with water from the Roush Draw river or stream.

Although Dunnagan has a low hazard potential and is currently in a not-rated condition, it is regulated by the Colorado Department of Water Resources. The dam has not been inspected since 1987, with an inspection frequency of every 6 years. Despite the moderate risk assessment rating, there are no specific risk management measures or emergency action plans in place for Dunnagan. The dam also features an uncontrolled spillway and has a maximum discharge of 378 cubic feet per second.

Enthusiasts of water resources and climate will find Dunnagan intriguing due to its historical significance in providing irrigation water in the region. With its location near Blanco, NM and the Roush Draw river, this dam plays a vital role in the agricultural landscape of Archuleta County. As efforts to manage and maintain water resources continue, Dunnagan stands as a reminder of the importance of infrastructure in sustaining agricultural practices in Colorado.

Year Completed

1949

Dam Length

569

Dam Height

14

River Or Stream

ROUSH DRAW

Primary Dam Type

Earth

Surface Area

20

Hydraulic Height

15

Drainage Area

1

Nid Storage

201

Structural Height

19

Hazard Potential

Low

Nid Height

19
       
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.