Thompson (Benton) Reservoir Report

Last Updated: December 13, 2025

Thompson (Benton) is a privately owned dam located in Benton, Oregon, near the city of WREN, on the BARK CREEK.


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Summary

Constructed in 1956, this Earth dam stands at a height of 41 feet and has a structural height of 43.5 feet, with a length of 450 feet. The dam serves primarily for recreational purposes, providing a storage capacity of 362 acre-feet and covering a surface area of 32.3 acres.

Managed by the Oregon Water Resources Department (OWRD), Thompson (Benton) is subject to state regulations and inspections to ensure its safety and compliance. With a significant hazard potential, this dam has not been rated for its condition assessment, highlighting the importance of ongoing monitoring and maintenance. The outlet gates are designed as Needle gates, and the dam has a maximum discharge capacity of 505 cubic feet per second.

Water resource and climate enthusiasts can find Thompson (Benton) an intriguing case study in dam management, showcasing the intersection of recreational use, regulatory oversight, and risk assessment in maintaining water infrastructure. As a part of the Portland District, the dam's location and characteristics offer a unique perspective on the challenges and opportunities involved in preserving water resources and ensuring public safety in the face of changing environmental conditions.

Year Completed

1956

Dam Length

450

Dam Height

41

River Or Stream

BARK CREEK

Primary Dam Type

Earth

Surface Area

32.3

Hydraulic Height

39

Drainage Area

3.2

Nid Storage

450

Structural Height

43.5

Outlet Gates

Needle

Hazard Potential

Significant

Nid Height

44
       
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.