Little Green Lake Outlet Reservoir Report

Last Updated: December 5, 2025

The Little Green Lake Outlet in Green Lake, Wisconsin is a gravity dam completed in 1934 primarily for recreation purposes.


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Summary

With a structural height of 11 feet and a length of 1000 feet, the dam has a normal storage capacity of 500 acre-feet and can discharge up to 75 cubic feet per second through a controlled spillway. The dam is regulated by the Wisconsin Department of Natural Resources and has a low hazard potential with a fair condition assessment as of July 2020.

Located in the Chicago District of the US Army Corps of Engineers, the Little Green Lake Outlet is situated in a picturesque area surrounded by natural beauty. The dam has a very high risk assessment ranking of 1, indicating the importance of regular inspections and maintenance. While the last inspection was conducted in June 2012 with a frequency of 10 years, the dam's emergency action plan (EAP) was last revised in January 2014. Despite the potential risks associated with the dam, its condition remains fair and it continues to provide recreational benefits to the local community.

Climate and water resource enthusiasts will appreciate the unique features of the Little Green Lake Outlet, including its historic significance and the role it plays in managing water levels and drainage in the area. As one of the many dams in Wisconsin regulated by the state, the Little Green Lake Outlet serves as a reminder of the importance of maintaining and managing water resources in a sustainable and responsible manner. With its controlled spillway and low hazard potential, the dam stands as a testament to the careful planning and engineering that goes into ensuring the safety and functionality of such structures in the face of changing climate conditions.

Years Modified

1998 - Other

Year Completed

1934

Dam Length

1000

Dam Height

11

River Or Stream

LITTLE GREEN LAKE OUTLET

Primary Dam Type

Gravity

Surface Area

466

Hydraulic Height

6

Drainage Area

4.8

Nid Storage

2300

Structural Height

11

Hazard Potential

Low

Nid Height

11
       
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.