Mcnett Reservoir Report

Last Updated: December 13, 2025

Mcnett, also known as Lake Joy, is a private water resource located in Lafayette, Wisconsin.


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Summary

Constructed in 1971 by the USDA NRCS, this dam serves primarily for recreational purposes. With a height of 40 feet and a storage capacity of 1000 acre-feet, Mcnett spans 1100 feet in length and covers a surface area of 55 acres.

Managed by the Wisconsin Department of Natural Resources, Mcnett is regulated, permitted, inspected, and enforced to ensure safety and compliance with state standards. The dam is classified as an earth-type structure with a controlled spillway system and a low hazard potential. Despite its fair condition assessment in 2020, Mcnett poses a very high risk, with a maximum discharge capacity of 150 cubic feet per second.

The surrounding Cottage Inn Branch-Pecatonica river system benefits from Mcnett's contribution to water management and recreation. With its strategic location and well-maintained facilities, Mcnett remains a vital resource for both the local community and water enthusiasts interested in the intersection of water resources and climate management.

Year Completed

1971

Dam Length

1100

Dam Height

40

River Or Stream

Cottage Inn Branch-Pecatonica

Primary Dam Type

Earth

Surface Area

55

Hydraulic Height

30

Drainage Area

2.3

Nid Storage

1000

Structural Height

40

Hazard Potential

Low

Nid Height

40
       
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.