Oconomowoc Lake Reservoir Report

Last Updated: December 5, 2025

Oconomowoc Lake, also known as Danforth, is a picturesque waterbody located in Waukesha, Wisconsin, with a rich history dating back to 1899 when the gravity dam was completed.


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Summary

This local government-owned reservoir spans 721 acres, offering ample opportunities for recreation and leisure activities. With a maximum storage capacity of 1810 acre-feet and a normal storage of 5000 acre-feet, the lake serves as a vital resource for the community.

The dam, standing at a height of 7 feet and a length of 60 feet, plays a crucial role in regulating water levels and ensuring the safety of the surrounding areas. Managed by the Wisconsin Department of Natural Resources, the dam undergoes regular inspections to maintain its fair condition and low hazard potential. Despite its age and years of modification, the dam continues to meet safety guidelines and serves as a key component in water resource management for the region.

Oconomowoc Lake's risk assessment indicates a very high risk level, emphasizing the importance of proactive risk management measures. With its controlled spillway and drainage area of 87 square miles, the lake remains a significant feature in the local landscape. As climate enthusiasts and water resource advocates, the unique characteristics of Oconomowoc Lake make it an intriguing site for further exploration and study in the realm of water management and climate resilience.

Years Modified

1939 - Other

Year Completed

1899

Dam Length

60

Dam Height

7

River Or Stream

OUTLET OCONOMOWOC LAKE

Primary Dam Type

Gravity

Surface Area

721

Hydraulic Height

1

Drainage Area

87

Nid Storage

5000

Structural Height

7

Hazard Potential

Low

Nid Height

7
       
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.