Rock Creek Reservoir Report

Last Updated: December 19, 2025

Rock Creek, also known as Triangle Reservoir, is a privately owned water source located in Owyhee, Idaho.


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Summary

This reservoir serves primarily for irrigation purposes and was completed in 1965. With a dam height of 36.5 feet and a storage capacity of 1184 acre-feet, Rock Creek plays a crucial role in supporting the agricultural needs of the region.

Managed by the Idaho Department of Water Resources, Rock Creek is regulated, inspected, and enforced to ensure its safety and functionality. The dam is classified as an earth dam with stone core types and is situated on the Rock Creek and North Boulder Creek. Despite being in fair condition, the reservoir poses a significant hazard potential, leading to a very high risk assessment. With a controlled spillway and a maximum discharge capacity of 2050 cubic feet per second, Rock Creek is a vital water resource in the area.

Located in the scenic Triangle Road area, Rock Creek offers a picturesque setting for water resource and climate enthusiasts. As one of the key irrigation sources in Owyhee County, this reservoir serves as a lifeline for agricultural activities in the region and plays a crucial role in water management and conservation efforts. Despite its risk potential, Rock Creek continues to be a vital asset for the local community and an essential component of the water infrastructure in Idaho.

Year Completed

1965

Dam Length

475

Dam Height

36.5

River Or Stream

ROCK CREEK NORTH BOULDER CREEK

Surface Area

74

Hydraulic Height

27.8

Drainage Area

54

Nid Storage

1184

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

37
       
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.