Jonbar Ranch Dam Reservoir Report
Last Updated: December 13, 2025
Jonbar Ranch Dam, located in Dallas County, Iowa, was completed in 1957 and is owned and regulated by a private entity.
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Summary
The dam, designed by USDA NRCS, serves multiple purposes including fire protection and creating a stock or small fish pond. With a dam height of 25 feet and a storage capacity of 104 acre-feet, the structure is primarily made of earth and sits on a soil foundation along the TR-Johnson Creek.
Despite being classified as having a low hazard potential, the dam is subject to state regulation, inspection, and enforcement by the Iowa DNR. Its risk assessment is moderate, with no specific risk management measures listed. The dam's spillway is uncontrolled, and it has not been rated for its condition assessment. Overall, Jonbar Ranch Dam is a significant water resource structure in the area, providing essential functions for fire protection and local wildlife while being closely monitored for safety and regulatory compliance.
Water resource and climate enthusiasts may find Jonbar Ranch Dam an intriguing case study due to its unique design, multiple purposes, and the balance between its benefits and risks. The dam's location along the Raccoon River in Iowa, coupled with its low hazard potential and moderate risk assessment, offer insights into the complexities of managing water infrastructure in a changing climate. As a privately owned and state-regulated structure, Jonbar Ranch Dam exemplifies the interconnectedness between public and private entities in ensuring water security and safety in the region.
Year Completed |
1957 |
Dam Length |
500 |
Dam Height |
25 |
River Or Stream |
TR-JOHNSON CREEK |
Primary Dam Type |
Earth |
Surface Area |
8 |
Drainage Area |
0.2 |
Nid Storage |
104 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
25 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Raccoon River At Van Meter
|
1640cfs |
Raccoon River Near West Des Moines
|
1300cfs |
Raccoon River At 63rd Street At Des Moines
|
587cfs |
Walnut Creek At Des Moines
|
10cfs |
Beaver Creek Near Grimes
|
183cfs |
Raccoon River At Fleur Drive
|
1200cfs |
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.
Jonbar Ranch Dam
360th Street Dallas County