Hartley Lake Reservoir Report

Last Updated: December 5, 2025

Hartley Lake, located in Itasca, Minnesota, is a state-regulated reservoir with a low hazard potential but a very high risk assessment.


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Summary

Constructed in 1938, this gravity dam stands at a height of 7.5 feet and has a structural height of 12 feet, providing a storage capacity of 1925 acre-feet. The reservoir covers an area of 318 acres and serves as a water resource for the surrounding area.

Managed by the Minnesota Department of Natural Resources, Hartley Lake has a controlled spillway and a fair condition assessment as of January 2018. Despite its low hazard potential, the reservoir is considered to have a very high risk due to potential factors that could impact its operation and safety. The dam's emergency action plan status and risk management measures are currently not available, highlighting the need for ongoing monitoring and assessment of this vital water resource in the Prairie River watershed.

The location of Hartley Lake in La Prairie, Minnesota, makes it an important feature in the local landscape, providing recreational opportunities and supporting ecological diversity. With its historical significance dating back to the Works Progress Administration era, this reservoir serves as a reminder of the importance of responsible water resource management in the face of changing climate patterns and environmental challenges.

Year Completed

1938

Dam Length

43

Dam Height

7.5

River Or Stream

PRAIRIE RIVER, WEST FORK

Primary Dam Type

Gravity

Surface Area

318

Hydraulic Height

4.2

Drainage Area

35

Nid Storage

1925

Structural Height

12

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

12
       
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.