Mehlhorn And Bassett Reservoir Report

Last Updated: December 13, 2025

Mehlhorn and Bassett is a private irrigation dam located in Baker, Oregon, along Clear Creek.


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Summary

Built in 1939, the dam stands at a height of 20 feet and has a hydraulic height of 17 feet. It serves the primary purpose of irrigation, with a storage capacity of 216 acre-feet and a drainage area of 1 square mile. Despite its age, the dam is classified as having a low hazard potential and is currently rated as "Not Rated" in terms of condition assessment.

The dam features a needle outlet gate and has a maximum discharge capacity of 230 cubic feet per second. With a length of 330 feet and a surface area of 27 acres, Mehlhorn and Bassett plays a vital role in water resource management in the area. The dam is regulated by the Oregon Water Resources Department and is subject to state permitting, inspection, and enforcement.

Located in Copperfield, the dam's surrounding area is represented by Congressman Greg Walden. The Walla Walla District of the US Army Corps of Engineers oversees the dam, ensuring its safe operation and maintenance. Water resource and climate enthusiasts can appreciate the significance of Mehlhorn and Bassett in supporting agricultural activities and water supply in the region, while also recognizing the importance of ongoing monitoring and regulatory compliance to ensure its continued safety and effectiveness.

Year Completed

1939

Dam Length

330

Dam Height

20

River Or Stream

CLEAR CREEK

Primary Dam Type

Earth

Surface Area

27

Hydraulic Height

17

Drainage Area

1

Nid Storage

216

Structural Height

20

Outlet Gates

Needle

Hazard Potential

Low

Nid Height

20
       
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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.