South Magnolia Watershed Site Z Reservoir Report
Last Updated: December 13, 2025
South Magnolia Watershed Site Z in Iowa is a local government-owned dam with a primary purpose of fire protection, stock, or small fish pond.
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Summary
Constructed in 1958 by USDA NRCS, this earth dam stands at a height of 44 feet and spans 570 feet in length. Located in Harrison County, it serves as a vital water resource for the area, providing a storage capacity of 146 acre-feet and covering a surface area of 3 acres.
Managed by the Iowa Department of Natural Resources, this dam on TR-WILLOW CREEK plays a key role in flood risk reduction in the region. Despite being rated as having a low hazard potential, it has not been assessed for condition since its last inspection in 1965. With a moderate risk assessment score of 3, there is a need for further evaluation and potential risk management measures to ensure the safety and effectiveness of this water resource infrastructure.
As a site with state jurisdiction, regulatory oversight, and permitting, South Magnolia Watershed Site Z is a critical component of the local ecosystem and climate resilience efforts. Its location in Missouri Valley, along with its historical significance and functional benefits, underscores the importance of proper maintenance and monitoring to safeguard the surrounding environment and communities from potential water-related risks.
Year Completed |
1958 |
Dam Length |
570 |
Dam Height |
44 |
River Or Stream |
TR-WILLOW CREEK |
Primary Dam Type |
Earth |
Surface Area |
3 |
Drainage Area |
0.69 |
Nid Storage |
146 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
44 |
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 Z