Leonard Ziesier No.1 Reservoir Report
Last Updated: December 13, 2025
Leonard Ziesier No.1 is a privately owned dam located in Gregory, South Dakota, along the Ponca Creek Offstream.
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Summary
Built in 1970, this earth dam stands at 30 feet high and stretches 371 feet in length, with a storage capacity of 19 acre-feet. While the dam is categorized as low hazard potential, its condition assessment is currently listed as "Not Rated," indicating a need for further evaluation.
Managed by the South Dakota Department of Environment and Natural Resources (DENR), Leonard Ziesier No.1 is subject to state regulations, permitting, inspections, and enforcement. Despite its age, the dam has not undergone any significant modifications in recent years, and its emergency action plan (EAP) status remains unclear. With a maximum discharge capacity of 460 cubic feet per second, the dam plays a crucial role in water resource management in the region.
For water resource and climate enthusiasts, Leonard Ziesier No.1 offers a fascinating case study in dam infrastructure and regulation. As a key component of the St. Paul District's water management system, this dam serves as a reminder of the importance of regular inspections and maintenance to ensure public safety and environmental protection. With its proximity to the Ponca Creek Offstream and its significant storage capacity, Leonard Ziesier No.1 continues to play a vital role in the local ecosystem and water supply network.
Year Completed |
1970 |
Dam Length |
371 |
Dam Height |
30 |
River Or Stream |
PONCA CREEK OFFSTREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
30 |
Nid Storage |
19 |
Hazard Potential |
Low |
Nid Height |
30 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Niobrara River At Mariaville
|
1650cfs |
Platte Creek Near Platte
|
3cfs |
Keya Paha R At Wewela Sd
|
54cfs |
Long Pine Creek Near Riverview
|
191cfs |
Niobrara River Nr. Verdel
|
517cfs |
Ponca Creek At Verdel
|
23cfs |
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.
Leonard Ziesier No.1