Trail Creek Reservoir Report

Last Updated: December 13, 2025

Trail Creek, located in the picturesque city of Sun Valley, Idaho, is a privately owned structure that plays a vital role in water resource management.


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Summary

Built in 1937, this Timber Crib dam stands at a height of 22.9 feet and has a normal storage capacity of 66.5 acre-feet. With a controlled spillway and a maximum discharge of 1060 cubic feet per second, Trail Creek ensures the efficient regulation of water flow from the Big Wood River.

Despite its fair condition assessment and high hazard potential, Trail Creek remains a crucial component of Idaho's water infrastructure, with state-regulated permitting, inspection, and enforcement measures in place to ensure its continued safety and functionality. The dam serves multiple purposes, including water storage and flood control, and its associated structures contribute to the efficient management of the surrounding drainage area of 62.8 square miles. As a key feature in the region's water management system, Trail Creek is a prime example of the importance of sustainable water resource practices in the face of climate change challenges.

Year Completed

1937

Dam Length

385

Dam Height

22.9

River Or Stream

TRAIL CREEK BIG WOOD RIVER

Surface Area

6.1

Hydraulic Height

18

Drainage Area

62.8

Nid Storage

66.5

Outlet Gates

Slide (sluice gate)

Hazard Potential

High

Foundations

Rock, Soil

Nid Height

23
       
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.