Upper Green Lake Reservoir Report

Last Updated: December 5, 2025

Upper Green Lake in Wisconsin is a gravity dam completed in 1869 with a primary purpose of recreation.


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Summary

Located in Green Lake County, this dam on the Puchyan River has a structural height of 8 feet and a storage capacity of 40,000 acre-feet. The dam is regulated by the Wisconsin Department of Natural Resources and undergoes regular inspections to ensure its safety and functionality.

With a surface area of 7346 acres and a drainage area of 115 square miles, Upper Green Lake provides both recreational opportunities and important water resource management for the region. The dam has a high hazard potential but is currently assessed to be in fair condition, with a moderate risk level. Emergency action plans are in place, and the dam is inspected every two years to maintain its integrity and safety.

Upper Green Lake is a vital water resource for the community, offering a picturesque setting for recreation while also serving as a key component of water management in the area. With its rich history dating back to the 19th century, this dam continues to play a crucial role in protecting and regulating water flow in Green Lake County. For water resource and climate enthusiasts, Upper Green Lake represents a blend of history, functionality, and environmental stewardship in one captivating location.

Years Modified

1994 - Other

Year Completed

1869

Dam Length

200

Dam Height

8

River Or Stream

PUCHYAN

Primary Dam Type

Gravity

Surface Area

7346

Hydraulic Height

5

Drainage Area

115

Nid Storage

40000

Structural Height

8

Hazard Potential

High

Nid Height

8
       
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.