Tremaine Reservoir Reservoir Report

Last Updated: December 5, 2025

Tremaine Reservoir, also known as Hay Lake, is a Federal-owned water storage structure located in Coconino County, Arizona.


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Summary

Built in 1952 by the USDA Natural Resource Conservation Service, the primary purpose of the reservoir is irrigation, with additional benefits for fire protection, stock watering, and fish and wildlife habitat. The dam is an earth type structure with a height of 30 feet and a length of 1935 feet, providing a storage capacity of 8000 acre-feet and a surface area of 265 acres.

Situated on the Jacks Canyon Tributary in the Two Guns area, Tremaine Reservoir plays a crucial role in water resource management and conservation efforts in the region. With a low hazard potential and fair condition assessment as of August 2020, the reservoir is maintained and regulated by the Forest Service to ensure safe operations. The risk assessment for the dam is categorized as moderate, indicating the need for ongoing monitoring and risk management measures to protect the surrounding communities and environment.

Despite its relatively small drainage area of 17 square miles, Tremaine Reservoir has a maximum discharge capacity of 7647 cubic feet per second, with an uncontrolled spillway width of 231 feet. Regular inspections every 10 years help to assess the structural integrity and safety of the dam, with the last assessment conducted in August 2020. As a valuable resource for irrigation and conservation in the region, Tremaine Reservoir continues to play a vital role in water management and climate resilience efforts.

Years Modified

2004 - Mechanical

Year Completed

1952

Dam Length

1935

Dam Height

30

River Or Stream

JACKS CANYON TRIB.

Primary Dam Type

Earth

Surface Area

265

Hydraulic Height

25

Drainage Area

17

Nid Storage

8000

Structural Height

30

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

30
       
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.