Pitt Lake Dam Reservoir Report

Last Updated: December 5, 2025

Pitt Lake Dam, located in Bonanza, Oregon, serves as a crucial irrigation source with a primary purpose of providing water for agricultural activities.


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Summary

Completed in 1920, this earth dam stands at a height of 11 feet and has a storage capacity of 122 acre-feet. The dam spans 310 feet in length and is situated along Barnes Valley Creek, a tributary to Pitt Lake.

Despite being classified with a low hazard potential, Pitt Lake Dam is state-regulated and undergoes regular inspections, permitting, and enforcement to ensure its structural integrity and safety. The dam features slide gates for outlet control and has a maximum discharge capacity of 118 cubic feet per second. While its condition assessment currently stands as "Not Rated," the dam continues to play a vital role in the local water resource management efforts, contributing to the sustainability of agricultural practices in the surrounding area.

With its historical significance dating back to the early 20th century, Pitt Lake Dam stands as a testament to the ingenuity and foresight of early water resource developers in Oregon. As a privately owned structure, it exemplifies the collaboration between private owners and state regulatory agencies in managing water resources efficiently and responsibly. As climate change continues to impact water availability and usage patterns, the maintenance and monitoring of dams like Pitt Lake will be crucial in ensuring a reliable and sustainable water supply for future generations.

Year Completed

1920

Dam Length

310

Dam Height

11

River Or Stream

BARNES VALLEY CREEK, TRIB TO

Primary Dam Type

Earth

Surface Area

12

Hydraulic Height

9

Drainage Area

0.6

Nid Storage

122

Structural Height

11

Outlet Gates

Slide (sluice gate)

Hazard Potential

Low

Nid Height

11
       
Seasonal Comparison

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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.