Dolores No. 1 Reservoir Report

Last Updated: December 6, 2025

Dolores No.


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Summary

1 is a privately owned irrigation dam located in Niobrara, Wyoming, along the Dolores Draw river. Completed in 1953, this Earth dam stands at a height of 27 feet with a hydraulic height of 22 feet and a structural height of 25 feet. With a storage capacity of 107 acre-feet, the dam primarily serves the purpose of irrigation, supporting agricultural activities in the region.

Despite being classified as having a low hazard potential and fair condition assessment, Dolores No. 1 is subject to state regulation, inspection, and enforcement to ensure its safety and functionality. With a spillway width of 30 feet and an uncontrolled spillway type, the dam is designed to manage potential flooding events. The last inspection in June 2019 revealed moderate risk, prompting the need for ongoing risk management measures to address any potential issues that may arise.

The dam, situated in a picturesque location with a surface area of 8 acres, plays a vital role in water resource management in the area. With Liz Cheney (R) as the Congressional Representative for the region, Dolores No. 1 remains a key infrastructure supporting the agriculture industry in Wyoming. As climate change continues to impact water resources, the maintenance and monitoring of structures like Dolores No. 1 will be crucial to ensure sustainable water management for the future.

Year Completed

1953

Dam Length

678

Dam Height

27

River Or Stream

DOLORES DRAW

Primary Dam Type

Earth

Surface Area

8

Hydraulic Height

22

Nid Storage

107

Structural Height

25

Outlet Gates

Valve - 1

Hazard Potential

Low

Foundations

Soil

Nid Height

27
       
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.