Collins Marsh Sub-Impound. Reservoir Report

Last Updated: December 5, 2025

Located in Manitowoc, Wisconsin, the Collins Marsh Sub-Impound is a state-owned recreational water resource that was completed in 1988.


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Summary

This sub-impound is part of the larger Collins Marsh Wildlife Area and is situated along the tributary of Mud Creek. With a dam height of 8 feet and a total length of 7500 feet, the sub-impound has a storage capacity of 350 acre-feet and covers a surface area of 140 acres, providing ample space for outdoor activities and wildlife habitat.

Managed by the Wisconsin Department of Natural Resources (WIDNR), the Collins Marsh Sub-Impound is regulated, inspected, and permitted by the state agency to ensure its safety and functionality. The spillway type for this earth dam is uncontrolled, with a spillway width of 7503 feet, allowing for controlled discharge during periods of high water flow. The hazard potential for this sub-impound is rated as low, with a moderate risk assessment score of 3, indicating a relatively stable and secure water resource for recreational use.

Visitors to the Collins Marsh Sub-Impound can enjoy activities such as fishing, boating, and wildlife observation in a serene and natural setting. With its strategic location and well-maintained infrastructure, this water resource serves as a valuable asset for the community and a sanctuary for various plant and animal species. Whether seeking relaxation or adventure, the Collins Marsh Sub-Impound offers a unique and enriching experience for water resource and climate enthusiasts alike.

Year Completed

1988

Dam Length

7500

Dam Height

8

River Or Stream

TRIB. MUD CREEK

Primary Dam Type

Earth

Surface Area

140

Hydraulic Height

6

Drainage Area

0.5

Nid Storage

350

Structural Height

8

Hazard Potential

Low

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.