Mclellan Reservoir Report

Last Updated: December 5, 2025

Mclellan, located in Coconino, Arizona, is a privately owned gravity dam on Johnson Canyon, built in 1907 for the primary purpose of serving as a Fish and Wildlife Pond.


°F

°F

mph

Wind

%

Humidity

Summary

With a height of 21 feet and a length of 293 feet, this structure has a storage capacity of 110 acre-feet and a surface area of 19 acres. The dam is regulated by the Arizona Department of Water Resources, with state permitting, inspection, and enforcement in place to ensure its safety and functionality.

Despite being categorized as having a low hazard potential, Mclellan is considered to have a moderate risk level (3) based on a risk assessment. The dam's condition assessment is currently marked as "Not Rated", with the last inspection conducted in September 2019. The spillway, which is uncontrolled, has a width of 120 feet. While Mclellan does not have associated locks or outlet gates, it remains an important structure for water resource management in the area, supporting wildlife habitats and contributing to the local ecosystem in Masonry #2 Dam.

Overall, Mclellan plays a vital role in maintaining the ecological balance of Johnson Canyon and the surrounding areas in Arizona. Its historical significance, combined with its functionality as a Fish and Wildlife Pond, highlights the importance of proper regulation and maintenance to ensure the safety and sustainability of this gravity dam for future generations of water resource and climate enthusiasts to appreciate and enjoy.

Year Completed

1907

Dam Length

293

Dam Height

21

River Or Stream

JOHNSON CANYON

Primary Dam Type

Gravity

Surface Area

19

Drainage Area

8

Nid Storage

110

Structural Height

33

Hazard Potential

Low

Foundations

Rock

Nid Height

33
       
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.