Jeffers Upper Reservoir Report

Last Updated: December 5, 2025

Jeffers Upper, located in Prior Lake, Minnesota, is a recreational dam managed by the local government and designed by the USDA NRCS.


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Summary

The dam, completed in 1981, stands at a height of 10 feet with a length of 133 feet, providing a storage capacity of 321 acre-feet. Situated on the Minnesota River, the dam's primary purpose is for recreation, offering a surface area of 3 acres for activities such as boating and fishing.

Despite its low hazard potential and satisfactory condition assessment, Jeffers Upper is subject to state regulation and inspection by the Minnesota Department of Natural Resources. The dam features an uncontrolled spillway and outlet gates, with a moderate risk assessment rating of 3. The surrounding area of Scott County, Minnesota, benefits from this structure for water resource management and flood control along the Minnesota River.

Overall, Jeffers Upper serves as both a functional and recreational asset for the community, showcasing the importance of sustainable water resource management and climate resilience in the region. With its earth dam construction and stone core types, the dam exemplifies the collaboration between local government and federal agencies to ensure the safety and enjoyment of residents and visitors alike.

Year Completed

1981

Dam Length

133

Dam Height

10

River Or Stream

MINNESOTA RIVER-TR

Primary Dam Type

Earth

Surface Area

3

Drainage Area

0.55

Nid Storage

321

Outlet Gates

Uncontrolled

Hazard Potential

Low

Foundations

Soil

Nid Height

10
       
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.