Lum Hollow Subwatershed M-3847 Reservoir Report
Last Updated: December 14, 2025
Located in Woodbury County, Iowa, the Lum Hollow Subwatershed M-3847 is a local government-owned dam designed by the USDA NRCS with a primary purpose of flood risk reduction.
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Summary
Completed in 1959, this earth dam stands at a height of 55 feet and spans 600 feet across Lum Hollow Creek. With a storage capacity of 279 acre-feet and a drainage area of 1.49 square miles, this dam plays a crucial role in managing water resources in the region.
Although classified as having a low hazard potential, the Lum Hollow Subwatershed M-3847 is subject to state regulation, inspection, and enforcement by the Iowa DNR. The dam's condition is currently rated as "Not Rated," with a moderate risk assessment score of 3. While no emergency action plan (EAP) or inundation maps have been prepared for this dam, it is important for stakeholders and local authorities to stay informed about its risk management measures and any potential updates to its operations to ensure the safety and sustainability of the surrounding community and environment.
Overall, the Lum Hollow Subwatershed M-3847 serves as a vital infrastructure for flood control and water resource management in the area. As climate change continues to impact weather patterns and precipitation levels, the proper maintenance and monitoring of this dam will be essential in safeguarding against potential risks and ensuring the continued protection of downstream communities and ecosystems.
Year Completed |
1959 |
Dam Length |
600 |
Dam Height |
55 |
River Or Stream |
LUM HOLLOW CREEK |
Primary Dam Type |
Earth |
Surface Area |
5.2 |
Drainage Area |
1.49 |
Nid Storage |
279 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
55 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
West Fork Ditch At Hornick
|
80cfs |
Maple River At Mapleton
|
323cfs |
Little Sioux River At Correctionville
|
327cfs |
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Missouri River At Decatur
|
14900cfs |
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.
Lum Hollow Subwatershed M-3847