Farley Lake Dam Reservoir Report
Nearby: Big Stone Lake Ortonville Twp 15
Last Updated: December 13, 2025
Farley Lake Dam, located in Milbank, South Dakota, is a local government-owned structure built in 1910 and regulated by the South Dakota Department of Agriculture and Natural Resources.
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Summary
This earth dam on the Whetstone River stands at 15 feet high and has a maximum storage capacity of 1,300 acre-feet. With a drainage area of 74 square miles, the dam serves the primary purpose of flood control and water storage for the surrounding region.
The dam features an uncontrolled spillway with a width of 150 feet, and despite its fair condition assessment in 2016, it has a high hazard potential. The last inspection on record was conducted in 2016, with an inspection frequency of every three years. The risk assessment for Farley Lake Dam indicates a moderate risk level of 3, prompting the need for ongoing risk management measures to ensure the safety and integrity of the structure in the face of potential climate challenges and water resource management needs.
As a crucial component of the local water infrastructure, Farley Lake Dam plays a vital role in safeguarding the community from flooding and providing essential water storage capacity. With its historical significance dating back over a century, the dam stands as a testament to early engineering efforts in the region and serves as a reminder of the ongoing importance of maintaining and managing water resources in the face of changing climate conditions.
Year Completed |
1910 |
Dam Length |
2800 |
Dam Height |
15 |
River Or Stream |
WHETSTONE RIVER |
Primary Dam Type |
Earth |
Hydraulic Height |
15 |
Drainage Area |
74 |
Nid Storage |
1300 |
Outlet Gates |
None |
Hazard Potential |
High |
Foundations |
Soil |
Nid Height |
15 |
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.
Farley Lake Dam