Point Of Rock Reservoir Report

Last Updated: December 15, 2025

Point of Rock is a privately owned dam located in Cassia, Idaho, along Marsh Creek and the Snake River.


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Summary

Built in 2004, this earth dam stands at a height of 30.2 meters and has a storage capacity of 358 acre-feet. With a drainage area of 87.9 square kilometers and a spillway width of 18 meters, Point of Rock plays a significant role in managing water resources in the region.

Managed by the Idaho Department of Water Resources, Point of Rock is subject to state regulation, inspection, and enforcement to ensure its safety and compliance with standards. The dam is classified as having a significant hazard potential, but its condition was assessed as satisfactory during the last inspection in July 2017. With its primary purpose listed as "Other" and utilizing stone core types and rock and soil foundation, Point of Rock serves as a key structure for water management and flood control in the area.

Despite being privately owned, Point of Rock provides essential functions for the community and surrounding environment. With its moderate risk assessment and satisfactory condition, this dam stands as a crucial infrastructure for water resource and climate enthusiasts to monitor and support for the continued resilience of the region.

Year Completed

2004

Dam Length

630

Dam Height

30.2

River Or Stream

MARSH CREEK SNAKE RIVER

Surface Area

42

Hydraulic Height

23

Drainage Area

87.9

Nid Storage

358

Outlet Gates

Slide (sluice gate)

Hazard Potential

Significant

Foundations

Rock, Soil

Nid Height

30
       
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.