Assman #4 Grade Stabilization Structure Reservoir Report
Last Updated: December 15, 2025
The Assman #4 Grade Stabilization Structure in the Boyer River floodplain of Crawford, Iowa, stands as a testament to the efforts of the USDA NRCS in mitigating erosion and improving water quality.
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Summary
Completed in 2010, this private-owned earth dam serves multiple purposes, including fire protection and providing a habitat for stock or small fish. With a height of 39 feet and a length of 370 feet, the structure has a storage capacity of 103 acre-feet and covers a surface area of 5.6 acres.
Situated in an area regulated by the Iowa DNR, this grade stabilization structure plays a crucial role in managing water flow along the TR-Boyer River. Its low hazard potential and not rated condition assessment reflect the efficiency of its design and maintenance. The dam's presence has not only enhanced the conservation efforts in the region but also contributes to the overall sustainability of the watershed. Enthusiasts of water resource management and climate resilience can find inspiration in the Assman #4 Grade Stabilization Structure as a model for effective land and water resource stewardship.
As a vital component in the Rock Island District, this structure symbolizes the collaborative efforts between private landowners, government agencies, and conservation organizations in ensuring the long-term health of the Boyer River ecosystem. By incorporating best practices in dam construction and management, the Assman #4 Grade Stabilization Structure serves as a beacon of innovation in sustainable water resource management. Its strategic location and design highlight the importance of proactive measures in adapting to the challenges posed by climate change and ensuring the resilience of water infrastructure in the face of evolving environmental conditions.
Year Completed |
2010 |
Dam Length |
370 |
Dam Height |
39 |
River Or Stream |
TR-Boyer River |
Primary Dam Type |
Earth |
Surface Area |
5.6 |
Drainage Area |
0.46 |
Nid Storage |
103 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
39 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Maple River At Mapleton
|
323cfs |
North Raccoon River Near Sac City
|
312cfs |
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Soldier River At Pisgah
|
112cfs |
Boyer River At Logan
|
417cfs |
Dam Data Reference
Condition Assessment
SatisfactoryNo 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
HighDams 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.
Assman #4 Grade Stabilization Structure