Portland #6 (Mt.Tabor) Reservoir Report

Last Updated: December 13, 2025

Portland #6, also known as Mt.


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Summary

Tabor, is a crucial water supply infrastructure located in Multnomah County, Oregon. Owned by the local government, this dam on the Bull Run River (offstream) was completed in 1911 and serves as a primary source of water for the city of Portland. With a dam height of 28 feet and a storage capacity of 230 acre-feet, Mt. Tabor plays a vital role in ensuring a reliable water supply for the region.

Maintained and regulated by the Oregon Water Resources Department, Mt. Tabor has a high hazard potential but is currently in satisfactory condition as of the last inspection in August 2020. The dam features a needle outlet gate and has a spillway width of 0. Despite its age, Mt. Tabor continues to meet the water supply needs of the community, showcasing the importance of effective infrastructure management and maintenance in the face of changing climate conditions.

With a history dating back over a century, Portland #6 (Mt. Tabor) stands as a testament to the resilience and foresight of water resource managers in Oregon. As climate change impacts become more pronounced, the maintenance and operation of dams like Mt. Tabor will be crucial in ensuring adequate water supply for future generations. As a key component of the region's water infrastructure, Mt. Tabor serves as a reminder of the intricate balance between water resource management, climate resilience, and community sustainability.

Year Completed

1911

Dam Length

1400

Dam Height

28

River Or Stream

BULL RUN RIVER (OFFSTREAM)

Primary Dam Type

Earth

Surface Area

12

Hydraulic Height

20

Nid Storage

230

Structural Height

28

Outlet Gates

Needle

Hazard Potential

High

Nid Height

28
       
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.