Van Donselar Dam Reservoir Report

Last Updated: December 13, 2025

Van Donselar Dam, located in Lake Keomah State Park in Mahaska County, Iowa, is a privately owned structure designed by the USDA NRCS and regulated by the Iowa DNR.


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Summary

Completed in 1998, this earth dam stands at a height of 30 feet and has a length of 372 feet, providing storage for fire protection, stock, or small fish pond purposes. The dam has a low hazard potential with a moderate risk assessment rating, making it an essential resource for water management in the area.

With a normal storage capacity of 69 acre-feet and a total storage of 120 acre-feet, Van Donselar Dam plays a crucial role in controlling water flow on the TR-South Skunk River. The dam's spillway type is uncontrolled, and it covers a surface area of 8.4 acres with a drainage area of 0.34 square miles. Although the dam has not been rated for condition assessment, it meets the necessary regulatory requirements for inspection, enforcement, and permitting, ensuring its operational efficiency and safety.

Managed by the Natural Resources Conservation Service, Van Donselar Dam remains a vital infrastructure for water resource and climate enthusiasts in the region. Its strategic location, design, and purpose contribute to the sustainable utilization of water for various needs while minimizing the risk of potential hazards. As a key component of the local water management system, the dam continues to play a significant role in enhancing environmental resilience and supporting the community's water supply needs.

Year Completed

1998

Dam Length

372

Dam Height

30

River Or Stream

TR- SOUTH SKUNK RIVER

Primary Dam Type

Earth

Surface Area

8.4

Drainage Area

0.34

Nid Storage

120

Hazard Potential

Low

Foundations

Soil

Nid Height

30
       
Seasonal Comparison

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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.