Deardorff Reservoir Report

Last Updated: December 13, 2025

Deardorff, Betty Jane is a privately owned dam located in Scotts Mills, Oregon, along the Little Coal Creek.


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Summary

Built in 1971, this earth dam stands at a height of 65 feet and has a storage capacity of 1300 acre-feet. It serves a primary purpose that is categorized as 'Other', with a significant hazard potential and a moderate risk assessment. The dam's spillway is uncontrolled, and it features slide gates as outlet gates.

The dam has a structural height of 68 feet and a hydraulic height of 58 feet, with a length of 450 feet. It covers a surface area of 60.3 acres and has a drainage area of 1 square mile. The dam is regulated by the Oregon Water Resources Department and undergoes regular inspections, with the last one being conducted in May 2018. The risk assessment for Deardorff, Betty Jane is classified as moderate, indicating the need for ongoing risk management measures to ensure the safety of the surrounding community and the water resources it protects.

Overall, Deardorff, Betty Jane is a vital water resource infrastructure in Clackamas County, Oregon, with a history of providing essential water storage and flood control benefits. As a privately owned dam, it is subject to state regulations and inspections to maintain its structural integrity and mitigate potential risks. Climate and water resource enthusiasts would find this dam's data intriguing, as it offers a glimpse into the engineering and management of a key piece of infrastructure that plays a critical role in water management in the region.

Year Completed

1971

Dam Length

450

Dam Height

65

River Or Stream

LITTLE COAL CREEK

Primary Dam Type

Earth

Surface Area

60.3

Hydraulic Height

58

Drainage Area

1

Nid Storage

1300

Structural Height

68

Outlet Gates

Slide (sluice gate)

Hazard Potential

Significant

Nid Height

68
       
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.