Oberon Lake No. 1 Reservoir Report

Last Updated: December 4, 2025

Oberon Lake No.


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Summary

1, also known as Hay's Lake or Lower Oberon, is a vital water resource located in Jefferson County, Colorado. Owned by the local government, this earth dam structure was completed in 1887 with the primary purpose of flood risk reduction along the Ralston Creek-OS. The dam stands at a height of 20 feet with a hydraulic height of 20 feet and a structural height of 28 feet, providing a maximum storage capacity of 69 acre-feet.

This historic water infrastructure covers a surface area of 3 acres and has a normal storage capacity of 6 acre-feet, serving as a low hazard potential structure with a satisfactory condition assessment. Despite its age, Oberon Lake No. 1 continues to be regulated and inspected by the Colorado Department of Water Resources, ensuring its continued functionality and safety. With a moderate risk assessment rating, the dam is equipped with an uncontrolled spillway and last underwent inspection in October 2012.

For water resource and climate enthusiasts, Oberon Lake No. 1 presents an intriguing blend of history, engineering, and environmental stewardship. As a crucial component in flood risk reduction efforts in the region, this earth dam serves as a testament to the importance of sustainable water management practices. With its low hazard potential and satisfactory condition, Oberon Lake No. 1 remains a key player in water resource management in the picturesque city of Arvada, Colorado.

Year Completed

1887

Dam Length

600

Dam Height

20

River Or Stream

RALSTON CREEK-OS

Primary Dam Type

Earth

Surface Area

3

Hydraulic Height

20

Nid Storage

69

Structural Height

28

Hazard Potential

Low

Nid Height

28
       
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.