Otter Tail Lake Reservoir Report

Last Updated: December 5, 2025

Otter Tail Lake, located in Minnesota, is a state-regulated body of water with a gravity dam that was completed in 1936 by MNDNR.


°F

°F

mph

Wind

%

Humidity

Summary

This lake serves multiple purposes, including flood control and recreation, with a low hazard potential and satisfactory condition assessment. With a storage capacity of 557,200 acre-feet and a surface area of 14,745 acres, Otter Tail Lake plays a crucial role in managing water resources in the region.

The dam on Otter Tail Lake is designed to control the flow of the Otter Tail River and has a spillway width of 105 feet. The lake's drainage area covers 1,160 square miles, and it has a maximum discharge capacity of 4,372 cubic feet per second. Despite its low hazard potential, the lake is subject to moderate risk, as assessed by regulatory agencies, and is inspected every eight years to ensure its structural integrity and safety measures are up-to-date.

Otter Tail Lake is a vital water resource in Otter Tail County, Minnesota, managed by the state agency MNDNR EWR. With its historical significance dating back to the 1930s, the lake continues to provide essential water management functions for the region. Enthusiasts of water resources and climate will appreciate the role that Otter Tail Lake plays in maintaining the ecological balance and supporting the recreational activities of the local community.

Year Completed

1936

Dam Length

125

Dam Height

6

River Or Stream

OTTER TAIL RIVER

Primary Dam Type

Gravity

Surface Area

14745

Drainage Area

1160

Nid Storage

557200

Structural Height

10

Hazard Potential

Low

Foundations

Unlisted/Unknown

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.