P.E.C. Headworks Reservoir Report

Last Updated: December 14, 2025

P.E.C.


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Summary

Headworks, located in Grant, Washington, is a private structure designed by Harza for the primary purpose of irrigation. Completed in 1990, this concrete dam stands at a height of 90 feet and has a hydraulic height of 76 feet. With a drainage area of 3600 square miles, P.E.C. Headworks plays a vital role in managing water resources in the region for irrigation, hydroelectric power generation, and recreation.

Managed by the Federal Energy Regulatory Commission (FERC), P.E.C. Headworks has a significant hazard potential and a high risk assessment rating. Although the condition assessment is not available, regular inspections are conducted to ensure the safety and integrity of the structure. The Emergency Action Plan (EAP) for the headworks was last revised in December 2020, indicating preparedness for any potential emergencies.

As a key component in the water resource infrastructure of Washington, P.E.C. Headworks serves as a crucial point for water management and distribution in the region. With its strategic location and design features, the dam plays a vital role in supporting various water-related activities while maintaining safety and regulatory compliance under the oversight of FERC.

Year Completed

1990

Dam Length

74

Dam Height

90

Primary Dam Type

Concrete

Hydraulic Height

76

Drainage Area

3600

Structural Height

90

Hazard Potential

Significant

Nid Height

90
       
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.