Mays Reservoir Report

Last Updated: December 14, 2025

Mays is a privately owned earth dam located on Muddy Creek in Jefferson, Oregon.


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Summary

Built in 1960, it serves primarily for irrigation purposes with a storage capacity of 457 acre-feet. The dam stands at a height of 37 feet, with a hydraulic height of 34 feet and a structural height of 38 feet. However, recent data indicates a high hazard potential and poor condition assessment, raising concerns for its safety and stability.

Despite being regulated by the Oregon Water Resources Department and subject to state permitting, inspection, and enforcement, Mays' poor condition assessment highlights the need for immediate attention and potential rehabilitation efforts. With a drainage area of 25.4 square miles and a maximum discharge of 40 cubic feet per second, any failure or breach could have significant implications for downstream communities and ecosystems. It is crucial for water resource and climate enthusiasts to monitor Mays closely and advocate for necessary maintenance and risk management measures to ensure its long-term safety and functionality.

Year Completed

1960

Dam Length

400

Dam Height

37

River Or Stream

MUDDY CREEK

Primary Dam Type

Earth

Surface Area

32

Hydraulic Height

34

Drainage Area

25.4

Nid Storage

457

Structural Height

38

Hazard Potential

High

Nid Height

38
       
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.