Tall Timber Lake Reservoir Report

Last Updated: December 13, 2025

Tall Timber Lake, nestled in the picturesque surroundings of Josephine County, Oregon, is a private irrigation reservoir that has been serving the local community since its completion in 1965.


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Summary

Situated along Salt Gulch Creek, this Earth dam structure stands at 28 feet high, with a storage capacity of 29 acre-feet and a surface area of 2.94 acres. With a primary purpose of irrigation, the reservoir plays a vital role in supporting agricultural activities in the region.

Managed by the Oregon Water Resources Department, Tall Timber Lake is regulated and inspected regularly to ensure its structural integrity and compliance with state guidelines. Despite its low hazard potential, the reservoir is subject to a six-year inspection frequency to maintain its functionality and safety standards. With a maximum discharge capacity of 90 cubic feet per second, the dam serves as a crucial water resource for the surrounding area, contributing to the sustainability of the local ecosystem and economy.

While the dam's condition assessment is currently marked as "Not Rated," ongoing monitoring and risk management measures are in place to safeguard against any potential hazards. As part of the Portland District, the reservoir falls under state jurisdiction and is an essential component of the regional water infrastructure. Water resource and climate enthusiasts visiting Tall Timber Lake can appreciate the intersection of human engineering and natural landscapes, highlighting the delicate balance between water management and environmental stewardship in this scenic corner of Oregon.

Year Completed

1965

Dam Length

255

Dam Height

28

River Or Stream

SALT GULCH CREEK

Primary Dam Type

Earth

Surface Area

2.94

Hydraulic Height

26

Drainage Area

0.87

Nid Storage

29

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.