Horihan-Herrick Reservoir Report
Nearby: Carrolton Twp 12 Horihan-Hazel Group
Last Updated: December 5, 2025
Horihan-Herrick, located in Whalan, Minnesota, is a privately owned dam designed by the USDA NRCS for flood risk reduction along the Root River.
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Summary
Completed in 1991, this earth dam stands at 36 feet tall with a length of 350 feet, providing a storage capacity of 34 acre-feet. Despite its low hazard potential and satisfactory condition assessment, the dam is regulated by the Minnesota Department of Natural Resources and undergoes regular inspections and enforcement to ensure its safety and effectiveness.
With a drainage area of 0.5 square miles and a maximum discharge of 300 cubic feet per second, Horihan-Herrick plays a crucial role in managing water flow and mitigating flood risks in the region. The dam's spillway, although uncontrolled, helps to maintain water levels within safe limits. While the dam's primary purpose is flood risk reduction, it also serves as a valuable resource for water resource and climate enthusiasts, showcasing the intersection of infrastructure, environmental stewardship, and community resilience in managing water resources.
As part of the St. Paul District of the USACE, Horihan-Herrick stands as a testament to the collaborative efforts between federal agencies, private owners, and state regulators in safeguarding communities against potential flood hazards. With its moderate risk assessment and regular monitoring, this dam exemplifies the importance of proactive risk management and the critical role of infrastructure in adapting to changing climate conditions and ensuring water security for all.
Year Completed |
1991 |
Dam Length |
350 |
Dam Height |
34 |
River Or Stream |
ROOT RIVER-TR |
Primary Dam Type |
Earth |
Surface Area |
4 |
Drainage Area |
0.5 |
Nid Storage |
34 |
Structural Height |
36 |
Hazard Potential |
Low |
Foundations |
Unlisted/Unknown |
Nid Height |
36 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Root River Near Pilot Mound
|
303cfs |
Root River Near Houston
|
472cfs |
South Fork Root River Near Houston
|
209cfs |
Upper Iowa River At Bluffton
|
264cfs |
Mississippi River At Winona
|
13700cfs |
Upper Iowa River At Decorah
|
137cfs |
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.
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Horihan-Herrick