Carl Reservoir Report

Last Updated: December 6, 2025

Carl, also known as Grandpa's Lake, is a privately owned Earth dam located in Lincoln, Wisconsin.


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Summary

Completed in 1957, this recreational structure stands at 11 feet tall and spans 2000 feet in length, with a maximum storage capacity of 160 acre-feet. Despite its low hazard potential, Carl is currently rated as being in poor condition, with a recent assessment conducted in November 2020.

Managed by the Wisconsin Department of Natural Resources, Carl is subject to state regulations, inspections, and enforcement measures to ensure its safety and functionality. With a drainage area of 2 square miles and a maximum discharge capacity of 250 cubic feet per second, this dam plays a crucial role in maintaining the water levels of the surrounding area. Although its condition is deemed poor, efforts are likely underway to address any necessary repairs or maintenance to mitigate potential risks and improve its overall performance.

For water resource and climate enthusiasts, Carl serves as a valuable case study in the management of recreational dams in Wisconsin. Its location, design, and historical significance offer insights into the challenges and opportunities associated with maintaining aging infrastructure in a changing climate. As efforts continue to assess and address its condition, Carl remains a focal point for ongoing discussions on water resource management and dam safety in the region.

Year Completed

1957

Dam Length

2000

Dam Height

11

Primary Dam Type

Earth

Surface Area

30

Hydraulic Height

7

Drainage Area

2

Nid Storage

160

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.