Billy Creek Reservoir Report

Last Updated: December 5, 2025

Located in Lemhi County, Idaho, Billy Creek is a privately owned irrigation structure that has been regulating water flow since it was completed in 1916.


°F

°F

mph

Wind

%

Humidity

Summary

With a height of 15.6 feet and a hydraulic height of 12.7 feet, this earth dam on the Salmon River watershed serves a vital role in supplying water for agricultural purposes in the region. The dam has a storage capacity of 75 acre-feet and covers a drainage area of 0.5 square miles.

Despite its historical significance, Billy Creek has a poor condition assessment as of the last inspection in 2016. The dam is classified as low hazard potential, but its risk assessment indicates a moderate level of risk. In terms of regulatory oversight, the Idaho Department of Water Resources is responsible for permitting, inspecting, and enforcing regulations related to the operation of Billy Creek. The structure also falls under state jurisdiction and is subject to state regulatory agencies.

As a key component of the irrigation infrastructure in the area, Billy Creek plays a crucial role in water resource management and agricultural production. Climate and water resource enthusiasts interested in understanding the impact of aging infrastructure on water availability and the environment may find the case of Billy Creek to be an intriguing example of the challenges facing dams in the western United States. The need for ongoing maintenance and improvements to ensure the safety and effectiveness of structures like Billy Creek highlights the complex relationship between water resources, climate variability, and infrastructure resilience.

Year Completed

1916

Dam Length

1520

Dam Height

15.6

River Or Stream

BILLY CREEK SALMON RIVER

Surface Area

16

Hydraulic Height

12.7

Drainage Area

0.5

Nid Storage

75

Hazard Potential

Low

Foundations

Rock, Soil

Nid Height

16
       
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.