Deiss Dam Reservoir Report
Nearby: Banek #1 Jr Schmidt #1
Last Updated: December 13, 2025
Deiss Dam, located in Mellette, South Dakota, is a state-regulated earth dam built in 1935 by the Works Progress Administration (WPA).
°F
°F
mph
Wind
%
Humidity
Summary
The dam stands at a height of 25 feet and spans 300 feet across the tributary of S. Branch Pine Creek. With a storage capacity of 190 acre-feet, Deiss Dam serves a vital role in water resource management in the region, providing irrigation water for agricultural purposes and ensuring a stable water supply for local communities.
Despite being classified as having a low hazard potential, Deiss Dam is subject to moderate risk, with a risk assessment rating of 3. While the dam's condition is currently not rated, it undergoes regular state inspections, permitting, and enforcement to ensure its structural integrity and safety. The spillway of the dam is uncontrolled, with a width of 30 feet, allowing for a maximum discharge of 880 cubic feet per second during peak flow events.
Deiss Dam's presence highlights the intersection of water resource management and climate resilience in South Dakota. As climate change continues to impact water availability and extreme weather events, the proper maintenance and management of dams like Deiss become crucial in safeguarding communities and ecosystems against potential risks and ensuring sustainable water management practices for the future.
Year Completed |
1935 |
Dam Length |
300 |
Dam Height |
25 |
River Or Stream |
TRIB. S.BRANCH PINE CREEK |
Primary Dam Type |
Earth |
Hydraulic Height |
25 |
Drainage Area |
1 |
Nid Storage |
190 |
Hazard Potential |
Low |
Nid Height |
25 |
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.
Deiss Dam