Held Watershed Site D-4 Reservoir Report
Last Updated: December 13, 2025
Held Watershed Site D-4 in Plymouth, Iowa, is a crucial Earth dam completed in 1978 for fire protection, stock, and small fish pond purposes.
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Summary
This site, managed by the local government and designed by the USDA NRCS, lies along the TR-Floyd River and serves multiple functions including flood risk reduction. With a dam height of 33 feet and a storage capacity of 123 acre-feet, this 450-foot long structure covers an area of 6.4 acres and drains a watershed area of 0.44 square miles.
Despite its low hazard potential, Held Watershed Site D-4 has a moderate risk assessment score of 3, indicating the need for ongoing monitoring and risk management measures. The dam is state-regulated by the Iowa DNR, with permitting, inspection, and enforcement conducted by state authorities. While the condition assessment is currently not rated, the site's emergency action plan (EAP) status is unclear, suggesting a potential area for improvement in terms of preparedness and response in case of emergencies.
Located just 2 miles from Hinton, Iowa, this site is a significant component of the local water resource infrastructure, providing essential services for both community safety and environmental conservation. With its strategic position along the TR-Floyd River and its multi-purpose design, Held Watershed Site D-4 represents a vital asset in the sustainable management of water resources and climate resilience efforts in the region.
Year Completed |
1978 |
Dam Length |
450 |
Dam Height |
33 |
River Or Stream |
TR-FLOYD RIVER |
Primary Dam Type |
Earth |
Surface Area |
6.4 |
Drainage Area |
0.44 |
Nid Storage |
123 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
33 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Floyd River At James
|
187cfs |
Perry Creek Near Milnerville
|
25cfs |
Missouri River At Sioux City
|
15100cfs |
Big Sioux River At Akron
|
816cfs |
Omaha Cr At Homer
|
45cfs |
Floyd River At Alton
|
36cfs |
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.
Held Watershed Site D-4