Stewart Mountain Reservoir Report

Last Updated: December 5, 2025

Stewart Mountain, a Federal-owned structure located in Mesa, Arizona, serves as a crucial water resource along the Salt River.


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Summary

Constructed in 1929 by the Bureau of Reclamation, this concrete dam stands at a height of 207 feet, with a storage capacity of 70,070 acre-feet and a surface area of 1,265 acres. With a primary purpose of hydroelectric power generation, Stewart Mountain also supports irrigation and water supply needs in the region.

The dam has undergone modifications in 1992 to enhance its hydraulic, seismic, and structural capabilities. With a hazard potential rated as high and a very high risk assessment score, Stewart Mountain is closely monitored by the Bureau of Reclamation. Although the condition assessment is not currently available, regular inspections are conducted to ensure the dam's safety and functionality. Additionally, an Emergency Action Plan (EAP) is in place, last revised in December 2020, to address any potential risks or emergencies.

As a significant infrastructure for water management and energy production, Stewart Mountain plays a vital role in the water resources and climate resilience of the region. With its impressive height, storage capacity, and historical significance, this dam stands as a testament to the enduring importance of water infrastructure in sustaining communities and ecosystems in Arizona.

Years Modified

1992 - Hydraulic, 1992 - Seismic, 1992 - Structural

Year Completed

1929

Dam Length

1260

Dam Height

207

River Or Stream

SALT RIVER

Primary Dam Type

Concrete

Surface Area

1265

Hydraulic Height

117

Drainage Area

121

Nid Storage

70070

Structural Height

207

Hazard Potential

High

Foundations

Rock

Nid Height

207
       
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.