Collins Marsh Reservoir Report

Last Updated: December 5, 2025

Collins Marsh, also known as Mud Creek, is a state-owned water resource located in Manitowoc, Wisconsin.


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Summary

This marsh serves primarily for recreational purposes, offering a serene setting for outdoor enthusiasts to enjoy. The dam at Collins Marsh, completed in 1965, stands at a height of 10 feet and spans 800 feet in length, with a storage capacity of 7,000 acre-feet and a surface area of 2,000 acres. The controlled spillway ensures proper water management, with a maximum discharge of 4,470 cubic feet per second.

Although classified as having a low hazard potential, the risk assessment for Collins Marsh indicates a very high risk level, emphasizing the need for proactive management and monitoring. The dam's condition is currently not rated, with the last inspection conducted in August 2011. The Emergency Action Plan (EAP) was last revised in January 2016, highlighting the importance of preparedness in case of emergencies. With state regulation, permitting, inspection, and enforcement in place, Collins Marsh serves as a vital water resource for the community, showcasing the intersection of water conservation and climate resilience.

Year Completed

1965

Dam Length

800

Dam Height

10

River Or Stream

MUD CREEK

Primary Dam Type

Gravity

Surface Area

2000

Hydraulic Height

3

Drainage Area

58.8

Nid Storage

7000

Structural Height

10

Hazard Potential

Low

Nid Height

10
       
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.