Lake Osakis 1 Reservoir Report

Last Updated: December 5, 2025

Lake Osakis 1, located in Todd County, Minnesota, is a picturesque water body with a primary purpose of recreation.


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Summary

Constructed in 1938 by the Works Progress Administration (WPA), this concrete dam stands at a height of 8 feet and spans 24 feet in length, providing a structural foundation for the lake's normal storage capacity of 8,849 acre-feet. With a surface area of 6,637 acres and a drainage area of 425 acres, Lake Osakis 1 offers ample opportunities for water enthusiasts to enjoy various recreational activities.

Despite its age, Lake Osakis 1 has been well-maintained, with a fair condition assessment as of 2009 and a low hazard potential. The dam features an uncontrolled spillway with a width of 20 feet, ensuring proper water release when needed. While the dam has not been modified in recent years, regular inspections every 8 years help ensure its continued safety and functionality. With a moderate risk assessment rating of 3, Lake Osakis 1 remains a popular destination for outdoor enthusiasts seeking a tranquil setting for boating, fishing, and other water-related activities in the heart of Minnesota's natural beauty.

Lake Osakis 1, with its historic construction and recreational focus, exemplifies the harmonious blend of human ingenuity and natural beauty. As a state-owned facility in Todd County, this dam serves not only as a key water resource for the local community but also as a beloved recreational spot for visitors seeking to connect with nature. Whether exploring the Long River that feeds into the lake or simply enjoying its serene waters, Lake Osakis 1 offers a glimpse into the rich tapestry of Minnesota's diverse landscapes and the importance of responsible water resource management in preserving these natural treasures for future generations.

Year Completed

1938

Dam Length

24

Dam Height

4

River Or Stream

LONG RIVER

Primary Dam Type

Concrete

Surface Area

6637

Drainage Area

425

Nid Storage

8849

Structural Height

8

Outlet Gates

None

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.