Ninemile Reservoir Report

Last Updated: December 5, 2025

Ninemile is a historically significant earth dam located on Nine Mile Creek in Gunnison, Utah.


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Summary

Built in 1900 for irrigation purposes, it stands at a structural height of 55 feet and has a hydraulic height of 46 feet. With a storage capacity of 4,300 acre-feet and a drainage area of 4 square miles, Ninemile plays a vital role in water resource management in the region.

Managed by the Utah Division of Water Rights, Ninemile is regulated, inspected, and enforced to ensure its safe operation. Despite being classified as having a high hazard potential, the dam is currently in fair condition, with the last inspection conducted in July 2020. The dam's emergency action plan status and risk assessment measures are yet to be determined, highlighting the importance of proactive risk management for this critical infrastructure.

Located within the jurisdiction of the Los Angeles District of the US Army Corps of Engineers, Ninemile serves as a reminder of the intersection between water resource management and climate resilience. As climate change continues to impact water availability and quality, the maintenance and upkeep of dams like Ninemile are essential for ensuring sustainable water use and mitigating potential risks to surrounding communities and ecosystems.

Year Completed

1900

Dam Length

825

River Or Stream

NINE MILE CREEK

Primary Dam Type

Earth

Hydraulic Height

46

Drainage Area

4

Nid Storage

4300

Structural Height

55

Hazard Potential

High

Nid Height

55
       
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.