Hopp Dam (Lower Site) Reservoir Report

Last Updated: December 12, 2025

Hopp Dam (Lower Site) in Malvern, Iowa, is a privately-owned earth dam designed by USDA NRCS for grade stabilization purposes.


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Summary

Completed in 2005, this dam has a height of 30 feet and a length of 268 feet, providing a storage capacity of 30 acre-feet. With a primary purpose of grade stabilization, it also serves as a fire protection, stock, or small fish pond.

Situated on a tributary to Silver Creek, this dam has a low hazard potential and has not been rated for its current condition. While it does not have outlet gates, it features a spillway width of 20 feet and a drainage area of 0.47 square miles. The dam's location in Mills County, Iowa, makes it a notable structure for water resource and climate enthusiasts interested in sustainable water management and environmental conservation efforts in the region.

Overall, Hopp Dam (Lower Site) is a vital infrastructure for flood control and water storage in the area, contributing to the protection of downstream communities and ecosystems. With its construction meeting state permitting and inspection requirements, this dam stands as a testament to effective collaboration between private ownership and government agencies in ensuring water resource sustainability and resilience against climate impacts in Iowa.

Year Completed

2005

Dam Length

268

Dam Height

30

River Or Stream

Trib to Silver Creek

Primary Dam Type

Earth

Surface Area

2

Drainage Area

0.47

Nid Storage

30

Outlet Gates

None

Hazard Potential

Low

Foundations

Soil

Nid Height

30
       
Seasonal Comparison

Weather Forecast

Dam Data Reference

Condition Assessment

Satisfactory
No 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

High
Dams 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.