Big Reservoir Report

Last Updated: December 13, 2025

Big Dam, also known as Big, is a gravity-type structure located in Lake County, Oregon.


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Summary

Built in 1966 by the Bureau of Land Management, this federal-owned dam serves as a vital water supply source for the area. Standing at a height of 10 feet with a length of 420 feet, Big Dam has a storage capacity of 875 acre-feet, with a normal storage level of 674 acre-feet. Despite its low hazard potential and fair condition assessment, the dam undergoes inspections every five years to ensure its safety and reliability.

Situated on the TRIB BIG LAKE stream, Big Dam plays a crucial role in managing water resources in the region. With a surface area of 640 acres and a maximum discharge rate of 31 cubic feet per second, the dam contributes to the overall water management strategy in Oregon. Although it lacks certain regulatory features like spillways and outlet gates, Big Dam continues to provide essential water supply services to the community while being monitored by the Bureau of Land Management for any necessary maintenance or improvements.

As a key asset owned and operated by the federal government, Big Dam exemplifies the importance of sustainable water resource management in the face of changing climate conditions. With its historical significance and ongoing relevance in the region, this gravity dam stands as a testament to the collaborative efforts between various agencies and stakeholders to safeguard water security for both current and future generations.

Year Completed

1966

Dam Length

420

Dam Height

10

River Or Stream

TRIB BIG LAKE

Primary Dam Type

Gravity

Surface Area

640

Hydraulic Height

10

Nid Storage

875

Structural Height

10

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

10
       
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.