Twenty-Sixth Street Stormwater Detention Basin Reservoir Report

Last Updated: December 12, 2025

The Twenty-Sixth Street Stormwater Detention Basin in Des Moines, Iowa, is a critical infrastructure designed by Snyder & Associates to mitigate flood risks in the area.


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Summary

Completed in 2007, this earth dam structure stands at a height of 43 feet and spans 305 feet in length, providing a storage capacity of 242 acre-feet to manage stormwater runoff from the surrounding 1.7 square mile drainage area. The dam is situated on Closes Creek and is regulated by the Iowa Department of Natural Resources to ensure proper inspection, enforcement, and permitting procedures are in place.

With a high hazard potential due to its location and purpose, the Twenty-Sixth Street Stormwater Detention Basin is maintained in a satisfactory condition as of the last assessment in May 2020. The structure serves as a crucial flood risk reduction measure in the region, contributing to the overall resilience of the community against extreme weather events. While the dam has an uncontrolled spillway and no outlet gates, its design and construction align with state regulations to protect downstream areas and ensure public safety.

Managed by the local government of Polk County, Iowa, this detention basin plays a key role in the city's stormwater management strategy. The basin's primary purpose is flood risk reduction, and it serves as a vital piece of infrastructure to safeguard the community against the impacts of climate change and increasing precipitation events. As climate enthusiasts and water resource advocates, understanding and supporting such critical infrastructure projects is essential to building a more sustainable and resilient future for our communities.

Year Completed

2007

Dam Length

305

Dam Height

43

River Or Stream

Closes Creek

Primary Dam Type

Earth

Drainage Area

1.7

Nid Storage

242

Hazard Potential

High

Foundations

Soil

Nid Height

43
       
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.