Pony Creek - Lower Reservoir Report

Last Updated: December 5, 2025

Pony Creek - Lower, also known as Merrit Reservoir, is a vital water resource located in Coos Bay, Oregon.


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Summary

Owned by a public utility, this dam serves the primary purpose of water supply, with a maximum storage capacity of 400 acre-feet and a surface area of 27.8 acres. Completed in 1988, the earth dam stands at 32 feet in height and spans 300 feet in length, providing essential water resources to the surrounding community.

Despite its importance, Pony Creek - Lower poses a high hazard potential due to its poor condition assessment. With a moderate risk rating of 3, this dam is in need of urgent attention to ensure its long-term safety and functionality. The inspection frequency is set at 1 year, with the last assessment conducted in September 2021. The dam features a slide (sluice gate) outlet gate and an uncontrolled spillway type, with a maximum discharge capacity of 1150 cubic feet per second.

As water resource and climate enthusiasts, it is essential to monitor and address the condition of Pony Creek - Lower to mitigate potential risks and ensure the continued availability of water supply in the region. With state regulation and oversight from the Oregon Water Resources Department, efforts should be made to improve the dam's condition and emergency preparedness measures to safeguard both the dam infrastructure and downstream communities from potential hazards.

Year Completed

1988

Dam Length

300

Dam Height

32

River Or Stream

Pony Creek

Primary Dam Type

Earth

Surface Area

27.8

Hydraulic Height

30

Drainage Area

3.86

Nid Storage

400

Structural Height

38

Outlet Gates

Slide (sluice gate)

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.