South Magnolia Watershed Site 4 Reservoir Report
Last Updated: December 13, 2025
South Magnolia Watershed Site 4, located in Harrison County, Iowa, is a significant water resource managed by the local government.
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Summary
This site, designed by the USDA NRCS, serves multiple purposes including fire protection, stock, and small fish pond. The dam, completed in 1958, is an earth structure standing at 34 feet tall and 515 feet long, with a storage capacity of 106 acre-feet and a surface area of 5.3 acres. The watershed site is regulated by the Iowa DNR and has state permitting, inspection, and enforcement in place to ensure its safety and functionality.
The South Magnolia Watershed Site 4 sits along the TR-WILLOW CREEK and is part of the Rock Island District, with a low hazard potential and a moderate risk assessment rating. Though last inspected in 1965, the dam remains in a not rated condition, indicating a need for further assessment. Despite its age, the dam continues to serve its intended purposes effectively, contributing to fire protection and water storage in the area. Enthusiasts of water resources and climate will find this site fascinating for its historical significance and the role it plays in local water management.
As a key feature in the region's water infrastructure, South Magnolia Watershed Site 4 offers a glimpse into the intersection of human intervention and natural resources. With its earth dam structure and regulated state jurisdiction, this site showcases the efforts to balance water resource management with environmental protection. Its location in Missouri Valley, Iowa, and association with the Natural Resources Conservation Service make it a valuable case study for those interested in sustainable water practices and climate resilience.
Year Completed |
1958 |
Dam Length |
515 |
Dam Height |
34 |
River Or Stream |
TR-WILLOW CREEK |
Primary Dam Type |
Earth |
Surface Area |
5.3 |
Drainage Area |
0.99 |
Nid Storage |
106 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
34 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Boyer River At Logan
|
417cfs |
Soldier River At Pisgah
|
112cfs |
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Big Papillion Cr
|
38cfs |
Missouri River At Omaha
|
17700cfs |
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.
South Magnolia Watershed Site 4