Illum Dam Reservoir Report
Nearby: Conte Dam Godfrey Dam
Last Updated: December 16, 2025
Illum Dam, located in Marshall County, Iowa, is a privately-owned structure designed by NRCS for fire protection and as a stock or small fish pond.
°F
°F
mph
Wind
%
Humidity
Summary
Completed in 2002, this earth dam stands at a height of 27 feet and spans a length of 490 feet, with a storage capacity of 117 acre-feet. The dam serves the purpose of regulating water flow in the TR- North Timber Creek and has a low hazard potential.
Despite its moderate risk assessment, Illum Dam has not been rated for its condition and does not have an Emergency Action Plan in place. The dam features an uncontrolled spillway with a width of 3 feet and is inspected, permitted, and regulated by the Iowa DNR. With a surface area of 9.4 acres and a drainage area of 0.35 square miles, the dam plays a crucial role in water resource management in the region. For water resource and climate enthusiasts, Illum Dam represents a fascinating case study in dam construction and management in the state of Iowa.
Year Completed |
2002 |
Dam Length |
490 |
Dam Height |
27 |
River Or Stream |
TR- NORTH TIMBER CREEK |
Primary Dam Type |
Earth |
Surface Area |
9.4 |
Drainage Area |
0.35 |
Nid Storage |
117 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
27 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Iowa River At Marshalltown
|
1040cfs |
Timber Creek Near Marshalltown
|
37cfs |
Indian Creek Near Mingo
|
79cfs |
South Fork Iowa River Ne Of New Providence
|
79cfs |
South Skunk River At Colfax
|
211cfs |
Richland Creek Near Haven
|
12cfs |
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.
Illum Dam