North Fork Reservoir Report

Last Updated: December 13, 2025

North Fork, also known as Rock Creek Reservoir, is a local government-owned water supply dam located in Philomath, Oregon.


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Summary

Built in 1960 by CH2M HILL, this earth dam stands at a height of 81 feet and has a maximum storage capacity of 305 acre-feet. The reservoir covers a surface area of 6.5 acres and serves the purpose of water supply for the surrounding area.

With a drainage area of 3.3 square miles and a maximum discharge of 1650 cubic feet per second, North Fork is a key infrastructure for water resource management in Benton County, Oregon. Despite being in fair condition according to the latest assessment in August 2020, the dam poses a high hazard potential. Regular inspections and enforcement by the Oregon Water Resources Department ensure the safety and reliability of this essential water supply structure.

Water resource and climate enthusiasts will be fascinated by the technical details of North Fork, including its design specifications and operational history. As a critical component of the local water supply system, this dam plays a vital role in ensuring water availability for the community while also posing unique challenges in terms of risk management and emergency preparedness. The intersection of engineering, environmental conservation, and public safety can be seen in the ongoing monitoring and maintenance efforts for North Fork, making it a noteworthy site for those interested in sustainable water infrastructure.

Year Completed

1960

Dam Length

580

Dam Height

81

River Or Stream

NORTH FORK ROCK CREEK

Primary Dam Type

Earth

Surface Area

6.5

Hydraulic Height

66

Drainage Area

3.3

Nid Storage

305

Structural Height

83

Hazard Potential

High

Nid Height

83
       
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.