Mayhew Lake Reservoir Report

Last Updated: December 12, 2025

Mayhew Lake, located in Becker, Minnesota, is a state-regulated body of water that serves multiple purposes, with a primary dam type of gravity.


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Summary

Built in 1949, this dam stands at a height of 8 feet, with a hydraulic height of 5 feet and a structural height of 9 feet. With a storage capacity of 3100 acre-feet and a drainage area of 28 square miles, Mayhew Lake covers a surface area of 128 acres and has a maximum discharge of 675 cubic feet per second.

Despite its low hazard potential, Mayhew Lake has a satisfactory condition assessment as of November 2017 and is inspected every 8 years to ensure its safety and functionality. The dam is associated with Mayhew Creek and is managed by the Minnesota Department of Natural Resources. With its historic significance dating back to the mid-20th century, Mayhew Lake remains an important water resource in Benton County, Minnesota, contributing to flood control and water storage in the region. For water resource and climate enthusiasts, Mayhew Lake offers a fascinating glimpse into the intersection of infrastructure, conservation, and environmental management in the North Star State.

Year Completed

1949

Dam Length

18

Dam Height

8

River Or Stream

MAYHEW CREEK

Primary Dam Type

Gravity

Surface Area

128

Hydraulic Height

5

Drainage Area

28

Nid Storage

3100

Structural Height

9

Hazard Potential

Low

Foundations

Unlisted/Unknown

Nid Height

9
       
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.