Rassmussen #1 Reservoir Report
Nearby: England #6 Anderson #1
Last Updated: December 13, 2025
Rassmussen #1 is a privately owned dam located in Mellette, South Dakota, built in 1957 for offstream water storage from TR Cottonwood Creek.
°F
°F
mph
Wind
%
Humidity
Summary
The dam has a height of 24 feet and a length of 456 feet, providing a maximum storage capacity of 96 acre-feet. It is regulated by the South Dakota Department of Environment and Natural Resources (DENR) and has a low hazard potential, with its condition currently not rated.
Although the dam has not been inspected recently and lacks specific emergency preparedness measures such as an Emergency Action Plan (EAP) or updated inundation maps, it still serves as an important water resource in the area. With a maximum discharge capacity of 280 cubic feet per second, Rassmussen #1 plays a key role in managing water flow and storage for the region. Despite its age, the dam continues to function effectively and safely, contributing to water management efforts in South Dakota.
As climate change continues to impact water resources and weather patterns, the maintenance and monitoring of dams like Rassmussen #1 become increasingly crucial. With its regulated status and low hazard potential, this dam represents a valuable asset in the region's water infrastructure. As water resource and climate enthusiasts, staying informed and advocating for the proper management and upkeep of structures like Rassmussen #1 is essential for ensuring the sustainability and resilience of our water systems in the face of changing environmental conditions.
Year Completed |
1957 |
Dam Length |
456 |
Dam Height |
24 |
River Or Stream |
TR COTTONWOOD CREEK OFFSTREAM |
Primary Dam Type |
Earth |
Hydraulic Height |
24 |
Nid Storage |
96 |
Hazard Potential |
Low |
Nid Height |
24 |
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.
Rassmussen #1