Margaret Lake Reservoir Report

Last Updated: December 5, 2025

Margaret Lake, also known as Marget Lake Dam, is a captivating water resource located in St.


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Summary

Francis, Minnesota. This state-regulated dam was completed in 1966 by the USDA NRCS and serves various purposes, including providing 2040 acre-feet of storage capacity and controlling the flow of the Rum River-TR. With a low hazard potential and satisfactory condition assessment, Margaret Lake is a key infrastructure managed by the Minnesota Department of Natural Resources.

The Earth-type dam stands at 18 feet high and 20 feet long, with a surface area of 115 acres and a drainage area of 1 square mile. Despite its lack of a spillway, the dam has proven to be effective in regulating water flow and managing the risk of flooding in the region. The dam's structure is buttressed and rests on an unlisted/unknown foundation, ensuring its stability and functionality for years to come.

With the support of state agencies and the USDA NRCS, Margaret Lake continues to play a crucial role in water management and climate resilience efforts in Isanti County, Minnesota. As a vital piece of infrastructure in the region, the dam's impact on water resources, wildlife habitats, and community safety underscores the importance of sustainable dam management practices in the face of changing environmental conditions.

Year Completed

1966

Dam Length

20

Dam Height

18

River Or Stream

RUM RIVER-TR

Primary Dam Type

Earth

Surface Area

115

Drainage Area

1

Nid Storage

2040

Structural Height

18

Outlet Gates

None

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

18
       
Seasonal Comparison

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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.