Nass Dam Reservoir Report
Last Updated: December 13, 2025
Nass Dam, located in Monona, Iowa, is a private earth dam completed in 1999 with a primary purpose of fire protection, stock, or small fish pond.
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Summary
The dam stands at a height of 44 feet and has a length of 637 feet, with a storage capacity of 224 acre-feet and a surface area of 11.2 acres. It is situated on the TR- SOLDIER RIVER and is regulated by the Iowa Department of Natural Resources.
Despite its low hazard potential and moderate risk assessment, Nass Dam has not been given a condition rating and lacks certain emergency preparedness measures such as an Emergency Action Plan (EAP). The dam does not have any outlet gates or locks and features an uncontrolled spillway type. The risk management measures for the dam are currently unspecified.
For water resource and climate enthusiasts, Nass Dam serves as an intriguing case study in dam infrastructure and management. With its unique design and purposes, as well as its location on the TR- SOLDIER RIVER, the dam presents a valuable opportunity for further exploration and analysis in the realm of water resource sustainability and climate resilience.
Year Completed |
1999 |
Dam Length |
637 |
Dam Height |
44 |
River Or Stream |
TR- SOLDIER RIVER |
Primary Dam Type |
Earth |
Surface Area |
11.2 |
Drainage Area |
0.89 |
Nid Storage |
224 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
44 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Soldier River At Pisgah
|
112cfs |
Maple River At Mapleton
|
323cfs |
Boyer River At Logan
|
417cfs |
Missouri River At Decatur
|
15500cfs |
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.
Nass Dam