Lake Ilo Dam Reservoir Report
Last Updated: December 6, 2025
Lake Ilo Dam, also known as the Chesley and Polly Dinkins Memorial Dam, is a Federal-owned structure located in Dunn Center, North Dakota.
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Summary
Managed by the Fish and Wildlife Service, this earth dam stands at a height of 38 feet and was completed in 1937 for recreational purposes. With a storage capacity of 31,326 acre-feet and a surface area of 990 acres, the dam serves as a popular spot for outdoor enthusiasts looking to enjoy water-based activities.
Situated on Spring Creek, the Lake Ilo Dam is regulated by the North Dakota State Water Commission and undergoes regular inspections to ensure its structural integrity. The dam has a spillway width of 347 feet and a high hazard potential, prompting the Fish and Wildlife Service to conduct frequent assessments and prepare emergency action plans. Despite being rated in fair condition as of the last inspection in 2017, the dam has seen modifications over the years to enhance its hydraulic and structural components, showcasing a commitment to maintaining its safety and functionality for the community.
Overall, Lake Ilo Dam serves as a vital water resource in North Dakota, offering both recreational opportunities and essential flood control measures. With its rich history dating back to the 1930s and ongoing efforts to ensure its safety and efficiency, this dam stands as a testament to the importance of sustainable water management practices in the face of changing climate conditions. For water resource and climate enthusiasts, Lake Ilo Dam represents a fascinating intersection of engineering ingenuity, environmental stewardship, and community resilience in the heart of the Midwest.
Years Modified |
1996 - Hydraulic, 1996 - Structural, 2003 - Hydraulic |
Year Completed |
1937 |
Dam Length |
1715 |
Dam Height |
38 |
River Or Stream |
SPRING CREEK |
Primary Dam Type |
Earth |
Surface Area |
990 |
Hydraulic Height |
37 |
Drainage Area |
129 |
Nid Storage |
31326 |
Structural Height |
51 |
Outlet Gates |
Slide (sluice gate) |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
51 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
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.
Lake Ilo Dam