Gerlach Dam Reservoir Report
Last Updated: December 13, 2025
Gerlach Dam, located in Linn Grove, Iowa, is a privately owned structure designed by USDA NRCS and regulated by the Iowa DNR.
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Summary
Completed in 1978, this earth dam stands at a height of 31 feet and serves multiple purposes, including fire protection and creating a small fish pond. With a storage capacity of 47 acre-feet and a surface area of 2.4 acres, Gerlach Dam plays a vital role in managing water resources in the area.
The dam, situated on TR-Cottonwood Creek, has a low hazard potential and a moderate risk assessment rating. Despite not being rated for its condition assessment, Gerlach Dam is subject to state permitting, inspection, and enforcement to ensure its safety and functionality. While it does not have an Emergency Action Plan (EAP) prepared, the structure meets regulatory guidelines and has not undergone any recent modifications, highlighting its reliability as a water management infrastructure in the region.
As a key component of water resource management in Buena Vista County, Iowa, Gerlach Dam underscores the importance of sustainable infrastructure for climate resilience. With its controlled spillway and modest storage capacity, the dam serves as a crucial asset for both local water supply and environmental conservation efforts. Its strategic location and design by the USDA NRCS demonstrate a commitment to safeguarding water resources and mitigating potential risks associated with climate variability.
Year Completed |
1978 |
Dam Length |
265 |
Dam Height |
31 |
River Or Stream |
TR-COTTONWOOD CREEK |
Primary Dam Type |
Earth |
Surface Area |
2.4 |
Drainage Area |
0.18 |
Nid Storage |
47 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
31 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Little Sioux River At Linn Grove
|
257cfs |
Ocheyedan River Near Spencer
|
59cfs |
Floyd River At Alton
|
36cfs |
Little Sioux River At Correctionville
|
327cfs |
North Raccoon River Near Sac City
|
312cfs |
Floyd River At James
|
187cfs |
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.
Gerlach Dam