Gannon Dam Reservoir Report
Last Updated: January 11, 2026
Gannon Dam, located in Jasper County, Iowa, is a privately owned earth dam designed by the USDA NRCS and completed in 1971.
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Summary
With a height of 29 feet and a length of 490 feet, the dam serves multiple purposes including fire protection and creating a small fish pond. It has a storage capacity of 106 acre-feet and covers a surface area of 3 acres, with a drainage area of 0.1 square miles.
The dam is regulated by the Iowa DNR and is subject to state permitting, inspection, and enforcement. Despite being classified as having a low hazard potential, the risk assessment for Gannon Dam indicates a moderate risk level. The spillway type is uncontrolled, and there are no outlet gates or associated structures. The dam is situated on TR-Sugar Creek and falls under the jurisdiction of the Rock Island District of the US Army Corps of Engineers.
Overall, Gannon Dam is a vital structure for water resource management in the area, providing essential services for fire protection and recreational activities like fishing. Although it is considered to have a moderate risk level, the dam remains well-maintained and its condition is currently not rated. With its strategic location and functional design, Gannon Dam continues to play a crucial role in water conservation efforts in Iowa.
Year Completed |
1971 |
Dam Length |
490 |
Dam Height |
29 |
River Or Stream |
TR-SUGAR CREEK |
Primary Dam Type |
Earth |
Surface Area |
3 |
Drainage Area |
0.1 |
Nid Storage |
106 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
29 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Indian Creek Near Mingo
|
79cfs |
South Skunk River At Colfax
|
211cfs |
Fourmile Creek Near Ankeny
|
9cfs |
Fourmile Creek At Des Moines
|
22cfs |
Des Moines River At 2nd Avenue
|
418cfs |
Des Moines River Near Saylorville
|
5190cfs |
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.
Gannon Dam