Whitestone Lake Dam Reservoir Report

Last Updated: December 16, 2025

Whitestone Lake Dam is a private rockfill dam located in Tonasket, Washington, along the Tr-Okanogan River.


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Summary

Completed in 1930, this dam primarily serves the purpose of recreation and irrigation, with a storage capacity of 2,720 acre-feet and a surface area of 192 acres. The dam stands at a hydraulic height of 9 feet and a structural height of 8 feet, providing low hazard potential and has not been rated for its condition assessment.

Owned by a private entity, Whitestone Lake Dam is regulated by the Washington Department of Ecology and is subject to state jurisdiction, permitting, inspection, and enforcement. The dam has a maximum discharge capacity of 825 cubic feet per second and is located in Congressional District 04, Washington, represented by Dan Newhouse. Despite lacking certain structural information such as dam volume and spillway type, Whitestone Lake Dam remains an important water resource in Okanogan County, Washington, supporting both recreational and agricultural activities in the region.

With its historical significance and ongoing role in water management, Whitestone Lake Dam serves as a vital asset for the community. While its condition assessment is incomplete, the dam's low hazard potential and adherence to state regulations ensure its continued operation for irrigation, recreation, and water resource management. As climate change continues to impact water resources, Whitestone Lake Dam exemplifies the importance of maintaining and monitoring infrastructure to meet the evolving needs of both humans and the environment in the face of a changing climate.

Year Completed

1930

Dam Length

375

River Or Stream

Tr-Okanogan River

Primary Dam Type

Rockfill

Surface Area

192

Hydraulic Height

9

Drainage Area

13.8

Nid Storage

2720

Structural Height

8

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

9
       
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.