Yoncalla Reservoir Reservoir Report

Last Updated: December 13, 2025

Yoncalla Reservoir, located in Yoncalla, Oregon, is a vital water supply source managed by the local government.


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Summary

Completed in 1983, this Earth dam stands at a height of 16 feet and has a storage capacity of 112 acre-feet. With a surface area of 8.6 acres, this reservoir on Adams Creek serves as a key water resource for the region.

Owned and regulated by the Oregon Water Resources Department, Yoncalla Reservoir plays a crucial role in ensuring water supply for the community. Despite its low hazard potential, the dam's condition is currently not rated. Regular inspections every 6 years help in monitoring its safety and structural integrity. The reservoir's proximity to the Portland District adds to its significance in the water resource management landscape.

Enthusiasts interested in water resources and climate can appreciate the ecological and hydrological importance of Yoncalla Reservoir in Douglas County, Oregon. As a primary water source, its role in sustaining the local environment and community underscores the need for proper management and maintenance. The reservoir's history, design, and regulatory oversight make it a fascinating subject for those passionate about water infrastructure and its impact on the surrounding ecosystem.

Year Completed

1983

Dam Length

2000

Dam Height

16

River Or Stream

ADAMS CREEK

Primary Dam Type

Earth

Surface Area

8.6

Hydraulic Height

14

Nid Storage

112

Structural Height

16

Hazard Potential

Low

Nid Height

16
       
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.