Nowak Dam Reservoir Report
Nearby: Gochenour Dam Cohrs Dam
Last Updated: December 13, 2025
Nowak Dam, located in Magnolia, Iowa, was completed in 2001 by the NRCS with a primary purpose of grade stabilization along TR-Allen Creek.
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Summary
This earth dam stands at 38 feet tall and spans 520 feet in length, with a maximum storage capacity of 18 acre-feet. The dam, built on a stone core and soil foundation, serves a drainage area of 0.15 square miles and has a low hazard potential.
Although Nowak Dam is not regulated by the state and has not been inspected or rated for condition, it is considered to have a moderate risk level. The dam features an uncontrolled spillway with a width of 2 feet and has not been modified since its completion. Despite lacking emergency action preparedness measures, the dam serves as a critical infrastructure for managing water resources in the region and mitigating potential flood risks along the TR-Allen Creek. For water resource and climate enthusiasts, Nowak Dam represents a noteworthy example of a privately owned structure contributing to the overall resilience of the local watershed.
Year Completed |
2001 |
Dam Length |
520 |
Dam Height |
38 |
River Or Stream |
TR-ALLEN CREEK |
Primary Dam Type |
Earth |
Surface Area |
2 |
Drainage Area |
0.15 |
Nid Storage |
18 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
38 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Soldier River At Pisgah
|
112cfs |
Boyer River At Logan
|
417cfs |
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Missouri River At Decatur
|
15500cfs |
Maple River At Mapleton
|
323cfs |
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.
Nowak Dam