Granlees Reservoir Report

Last Updated: December 5, 2025

Granlees is a historic gravity dam located in Rancho Murieta, California, along the picturesque Cosumnes River.


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Summary

Built in 1921, this dam serves multiple purposes including flood risk reduction, irrigation, and water supply, making it a vital resource in the region. With a height of 17 feet and a storage capacity of 75 acre-feet, Granlees plays a critical role in managing water resources in Sacramento County.

Managed by a public utility, Granlees is regulated by the California Department of Water Resources (DWR) and undergoes regular inspections to ensure its safety and functionality. Despite its low hazard potential, the dam is deemed to be in satisfactory condition, with the last assessment conducted in September 2017. As a key infrastructure for flood risk reduction in the area, Granlees provides essential protection for local communities and supports agricultural and recreational activities along the Cosumnes River.

With its rich history and ongoing commitment to water management, Granlees stands as a testament to the importance of sustainable infrastructure in mitigating the impacts of climate change. As climate enthusiasts, we recognize the significance of dams like Granlees in safeguarding our water resources and enhancing resilience in the face of environmental challenges. As we continue to address the evolving needs of our water systems, Granlees remains a symbol of innovation and stewardship in ensuring a sustainable future for generations to come.

Year Completed

1921

Dam Length

364

Dam Height

17

River Or Stream

Cosumnes River

Primary Dam Type

Gravity

Surface Area

30

Hydraulic Height

12

Drainage Area

535

Nid Storage

75

Hazard Potential

Low

Nid Height

17
       
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.