Pine Mountain Lake Reservoir Report

Last Updated: December 5, 2025

Pine Mountain Lake, located in Cass County, Minnesota, is a state-regulated reservoir on the Pine River.


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Summary

Built in 1936 by the Works Progress Administration (WPA-C), this gravity dam stands at a height of 6 feet and has a maximum storage capacity of 126,737 acre-feet. The dam serves various purposes, including flood control, recreation, and water supply for the surrounding area.

With a surface area of 1,612 acres and a drainage area of 44.1 square miles, Pine Mountain Lake provides a picturesque setting for outdoor enthusiasts to enjoy activities such as boating, fishing, and wildlife observation. The dam is under the jurisdiction of the Minnesota Department of Natural Resources, which oversees its permitting, inspection, and enforcement to ensure its safe operation. Despite its low hazard potential, the dam is regularly assessed and has been deemed to be in satisfactory condition as of the last inspection in 2015.

Pine Mountain Lake's historical significance, combined with its recreational opportunities and vital role in water resource management, make it a valuable asset in Minnesota's landscape. Climate and water resource enthusiasts can appreciate the intricate design and functionality of this gravity dam, which continues to play a crucial role in maintaining the ecological balance and water supply in the region.

Year Completed

1936

Dam Length

45

Dam Height

6

River Or Stream

PINE RIVER

Primary Dam Type

Gravity

Surface Area

1612

Hydraulic Height

2.75

Drainage Area

44.1

Nid Storage

126737

Structural Height

7

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

7
       
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.