Loon Lake Reservoir Report

Last Updated: December 7, 2025

Loon Lake, located in Jackson, Minnesota, is a gravity dam on Loon Creek with a primary purpose that goes beyond typical water resource management.


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Summary

Completed in 1935, this dam stands at 8 feet tall and spans 30 feet in length, providing a storage capacity of 5000 acre-feet for its 707-acre surface area. Despite its low hazard potential, the dam received a satisfactory condition assessment during its last inspection in 2015, ensuring its structural integrity for the foreseeable future.

Owned by the local government and situated in the Omaha District, Loon Lake serves as a vital resource for the surrounding community, with a normal storage capacity of 3000 acre-feet and a maximum discharge rate of 265 cubic feet per second. Its relatively small drainage area of 32 square miles highlights its localized impact on water management in the region. With its buttress core design and unlisted foundation type, this dam exemplifies the engineering ingenuity of its time while also incorporating modern safety standards to meet regulatory requirements.

As climate change continues to impact water resources worldwide, the significance of dams like Loon Lake in managing water availability and flood control cannot be understated. With Jim Hagedorn (R) representing the area in Congress, the importance of maintaining and updating infrastructure like this dam remains a priority to ensure the resilience of local communities in the face of changing environmental conditions.

Year Completed

1935

Dam Length

30

Dam Height

7

River Or Stream

LOON CREEK

Primary Dam Type

Gravity

Surface Area

707

Hydraulic Height

0.5

Drainage Area

32

Nid Storage

5000

Structural Height

8

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

8
       
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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.