Smokey Hollow Subwatershed Site 1 Reservoir Report
Last Updated: December 14, 2025
Smokey Hollow Subwatershed Site 1, located in Woodbury County, Iowa, is a vital flood risk reduction structure designed by H,W,S, Inc.
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Summary
and Hoskins Western Sonderegger Inc. The earthen dam, completed in 1986, stands at a height of 59 feet and spans 517 feet in length, with a maximum storage capacity of 475 acre-feet. Situated along the TR-Smokey Hollow River, this site plays a crucial role in managing water flow and protecting the surrounding areas from potential flooding.
Managed by the Iowa Department of Natural Resources, Smokey Hollow Subwatershed Site 1 is subject to regular inspections, with the last assessment conducted in June 2020, yielding a satisfactory condition rating. Despite its high hazard potential, the dam is deemed to have a moderate risk level, indicating the importance of continued monitoring and risk management measures. With a drainage area of 1.51 square miles and a surface area of 7.9 acres, this structure serves as a key component in safeguarding the local community of Smithland and its residents from the impacts of extreme weather events.
As a significant infrastructure for flood risk reduction in the region, Smokey Hollow Subwatershed Site 1 underscores the collaboration between local government authorities and the Natural Resources Conservation Service in safeguarding water resources and mitigating climate-related threats. With its strategic location and critical role in managing water flow, this site exemplifies the importance of effective dam infrastructure in ensuring the resilience of communities against environmental challenges.
Year Completed |
1986 |
Dam Length |
517 |
Dam Height |
59 |
River Or Stream |
TR- SMOKEY HOLLOW |
Primary Dam Type |
Earth |
Surface Area |
7.9 |
Drainage Area |
1.51 |
Nid Storage |
475 |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
59 |
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
|
15500cfs |
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.
Smokey Hollow Subwatershed Site 1