Stoneridge (No. 19) Reservoir Report

Last Updated: December 5, 2025

Stoneridge (No.


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Summary

19) is a vital flood risk reduction structure located in Maricopa County, Arizona. Completed in 1973, this earth dam stands at a height of 25 feet and has a capacity to store 163 acre-feet of water from the Colony Wash. The dam's primary purpose is flood risk reduction, with a spillway width of 100 feet to handle a maximum discharge of 6950 cubic feet per second.

Managed by the Arizona Department of Water Resources, Stoneridge (No. 19) is subject to regular state inspections and enforcement measures to ensure its structural integrity and safety. With a high hazard potential and a moderate risk assessment score of 3, the dam is considered to be in satisfactory condition as of the last assessment in February 2018. Despite its critical role in protecting Fountain Hills and surrounding areas from flooding, the dam's normal storage level is reported to be zero, indicating that it is currently not holding any water for non-emergency purposes.

Water resource and climate enthusiasts can appreciate the engineering feat behind Stoneridge (No. 19) as it continues to serve its essential function in mitigating flood risks in the region. With a strategic location at S22, T3N, R6E and a capacity to store water from the Colony Wash, this stone-core earth dam stands as a testament to effective water resource management in Arizona. Its high hazard potential underscores the importance of regular inspections and maintenance to ensure the safety of downstream communities in the face of potential flood events.

Year Completed

1973

Dam Length

370

Dam Height

25

River Or Stream

COLONY WASH

Primary Dam Type

Earth

Surface Area

11

Hydraulic Height

25

Drainage Area

0.7

Nid Storage

163

Structural Height

38

Hazard Potential

High

Foundations

Soil

Nid Height

38
       
Seasonal Comparison

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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.