Rock Creek (Wasco) Reservoir Report

Last Updated: December 13, 2025

Rock Creek (Wasco) is a vital water resource in Oregon, serving the local community for irrigation purposes since its completion in 1947.


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Summary

Managed by the Natural Resources Conservation Service, this earth dam stands at a height of 51 feet and has a storage capacity of 1500 acre-feet. The dam spans 780 feet across and has a normal storage level of 1280 acre-feet, covering a surface area of 106 acres.

Located in Tygh Valley, Wasco County, Rock Creek (Wasco) regulates water flow from Rock, North Fork Gate, and Threemile streams, with a maximum discharge capacity of 904 cubic feet per second. Despite being classified as having a high hazard potential, the dam's condition assessment as of October 2020 was deemed fair. It is subject to regular state inspection, permitting, and enforcement by the Oregon Water Resources Department, ensuring its continued operational safety and efficiency.

Enthusiasts of water resources and climate will appreciate the strategic importance of Rock Creek (Wasco) in supporting agricultural activities in the region. With its moderate risk assessment rating, the dam plays a crucial role in water management and conservation efforts, highlighting the significance of sustainable infrastructure for adapting to changing climate conditions. As a key component of the local water supply system, Rock Creek (Wasco) stands as a testament to effective collaboration between state agencies and local government in safeguarding water resources for future generations.

Year Completed

1947

Dam Length

780

Dam Height

51

River Or Stream

ROCK, NORTH FORK GATE, & THREEMILE

Primary Dam Type

Earth

Surface Area

106

Hydraulic Height

49

Drainage Area

10

Nid Storage

1500

Structural Height

51

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

51
       
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.