John Orr Reservoir Report

Last Updated: December 26, 2025

John Orr is a privately owned dam located in Ione, California, specifically on the Tr Jackson Cr river.


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Summary

Completed in 1959, this earth dam stands at 20 feet high with a hydraulic height of 16 feet and a length of 590 feet. Its primary purpose is for water supply, serving irrigation, recreation, and water supply needs in the area.

Managed by the California Department of Water Resources, John Orr is regulated, permitted, inspected, and enforced under state jurisdiction. With a storage capacity of 152 acre-feet and a drainage area of 0.85 square miles, this dam has a low hazard potential and is assessed to be in satisfactory condition as of September 2017. Despite its age, John Orr remains a vital infrastructure for water resource management in Amador County, California.

The dam's last inspection was conducted in October 2020, with a regular inspection frequency of once per year. While no emergency action plan (EAP) or risk assessment information is currently available, the dam's condition and hazard potential are continuously monitored to ensure the safety and reliability of its operations. As a key component in the water supply infrastructure of the region, John Orr plays a crucial role in sustaining water resources and adapting to the challenges of a changing climate.

Year Completed

1959

Dam Length

590

Dam Height

20

River Or Stream

Tr Jackson Cr

Primary Dam Type

Earth

Surface Area

36

Hydraulic Height

16

Drainage Area

0.85

Nid Storage

152

Hazard Potential

Low

Nid Height

20
       
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.