Central City Milldam Reservoir Report

Last Updated: December 5, 2025

Central City Milldam, located in Linn County, Iowa, is a gravity dam built in 1965 along the Wapsipinicon River for recreational purposes.


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Summary

The dam stands at a height of 14 feet and spans a length of 490 feet, with a storage capacity of 170 acre-feet and a surface area of 25 acres. Despite its low hazard potential, the dam's risk assessment indicates a moderate level of risk, emphasizing the need for ongoing monitoring and management measures.

Managed by the local government and regulated by the Iowa Department of Natural Resources, Central City Milldam serves as a popular spot for outdoor activities such as fishing, boating, and wildlife observation. While the dam has not been rated for its condition, the last inspection conducted in 1989 revealed no immediate concerns. The dam's uncontrolled spillway type and soil foundation suggest a reliance on natural drainage processes for flood control, highlighting the importance of regular inspections and maintenance to ensure its continued safety and functionality.

As climate change continues to impact water resources and weather patterns, Central City Milldam serves as a vital infrastructure for both recreation and flood management in the region. With its historical significance and scenic location along the Wapsipinicon River, the dam remains a focal point for water resource and climate enthusiasts seeking to understand the interconnectedness of human activities and natural systems in a changing environment.

Year Completed

1965

Dam Length

490

Dam Height

14

River Or Stream

WAPSIPINICON RIVER

Primary Dam Type

Gravity

Surface Area

25

Drainage Area

1263

Nid Storage

170

Hazard Potential

Low

Foundations

Soil

Nid Height

14
       
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.