Harrison County Roadgrade Dam 18-79-43 Reservoir Report
Nearby: Schwertley Dam Olsen Dam
Last Updated: December 14, 2025
Harrison County Roadgrade Dam 18-79-43, located in Iowa along the TR-WILLOW CREEK, was completed in 1959 with a primary purpose of fire protection, stock, or small fish pond.
°F
°F
mph
Wind
%
Humidity
Summary
This earth dam stands at a height of 66 feet and stretches 395 feet in length, providing a storage capacity of 486 acre-feet and covering a surface area of 14.1 acres. Managed by the local government and designed by USDA NRCS, this dam is regulated by the Iowa DNR and undergoes regular inspections to ensure its structural integrity and safety.
With a significant hazard potential and a moderate risk assessment rating, Harrison County Roadgrade Dam 18-79-43 is classified as satisfactory in its condition assessment. The dam has a controlled spillway type with a width of 2 feet and is equipped for emergency situations with an inspection frequency of 5 years. The surrounding area, including the Missouri River, benefits from the water resource management provided by this dam, serving as a vital asset for the community's needs for firefighting, livestock, and recreational purposes.
As a part of the local government's infrastructure, this dam plays a crucial role in water resource management and climate resilience in Harrison County, Iowa. With its soil foundation and uncontrolled spillway, the dam serves as a reliable structure for water storage and flood control, ensuring the safety of the surrounding areas. Through continued monitoring and maintenance, Harrison County Roadgrade Dam 18-79-43 remains a key component in the region's efforts to manage water resources effectively and mitigate potential risks associated with dam failure.
Year Completed |
1959 |
Dam Length |
395 |
Dam Height |
66 |
River Or Stream |
TR-WILLOW CREEK |
Primary Dam Type |
Earth |
Surface Area |
14.1 |
Drainage Area |
1.45 |
Nid Storage |
486 |
Hazard Potential |
Significant |
Foundations |
Soil |
Nid Height |
66 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Boyer River At Logan
|
417cfs |
Soldier River At Pisgah
|
112cfs |
Little Sioux River Near Turin
|
1040cfs |
Monona-Harrison Ditch Near Turin
|
158cfs |
Big Papillion Cr
|
38cfs |
Missouri River At Omaha
|
17700cfs |
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.
Harrison County Roadgrade Dam 18-79-43