Sunriver Effluent Lagoon Reservoir Report

Last Updated: December 14, 2025

Sunriver Effluent Lagoon, also known as Lake Penhollow, is a privately owned water resource located in Deschutes, Oregon.


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Summary

This off-channel lagoon was designed by Dave Evans and is regulated by the Oregon Water Resources Department. Completed in 1998, the earth dam stands at a height of 30 feet, with a maximum storage capacity of 244 acre-feet and a normal storage level of 202.4 acre-feet. The lagoon covers an area of 13.4 acres and plays a crucial role in water management in the region.

With a high hazard potential but a satisfactory condition assessment as of October 2020, Sunriver Effluent Lagoon is subject to regular inspections to ensure its safety and functionality. The lagoon primarily serves purposes beyond flood control and irrigation, reflecting its unique role in the local water resource infrastructure. The lagoon's proximity to the Portland District of the US Army Corps of Engineers highlights its significance in the area's water management and environmental conservation efforts.

As a key water resource in Oregon, Sunriver Effluent Lagoon stands as a testament to effective dam design and regulation. Its role in maintaining water quality and supporting local ecosystems underscores the importance of responsible water management practices in the face of climate change and increasing water scarcity. Enthusiasts of water resources and climate resilience can appreciate the complexities and significance of this privately owned lagoon in Deschutes County, Oregon.

Year Completed

1998

Dam Height

30

River Or Stream

OFF CHANNEL

Primary Dam Type

Earth

Surface Area

13.4

Hydraulic Height

26

Nid Storage

244

Hazard Potential

High

Foundations

Rock

Nid Height

30
       
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.