South Fork Reservoir Report
Nearby: Roger's Folly No. 2 Horn Creek
Last Updated: December 13, 2025
South Fork is a private irrigation dam located in Johnson, Wyoming, along the South Fork Crazy Woman River.
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Summary
Completed in 1973, this earth dam stands at 26 feet high and spans 1800 feet in length, providing a storage capacity of 317 acre-feet. Despite its low hazard potential, the dam's condition assessment is rated as poor, with a risk assessment indicating moderate risk level.
The dam features a slide (sluice gate) for outlet gates and an uncontrolled spillway with a width of 250 feet. While the dam is state regulated and subject to inspection, its last assessment in August 2018 revealed a need for maintenance and improvement. The surrounding area covers 25 acres, serving as a crucial resource for irrigation in the region. Water resource and climate enthusiasts may find South Fork to be an intriguing structure with a mix of historical significance and ongoing challenges related to its condition and risk management.
Year Completed |
1973 |
Dam Length |
1800 |
Dam Height |
26 |
River Or Stream |
SOUTH FORK CRAZY WOMAN |
Primary Dam Type |
Earth |
Surface Area |
25 |
Hydraulic Height |
21 |
Nid Storage |
317 |
Structural Height |
26 |
Outlet Gates |
Slide (sluice gate) - 1 |
Hazard Potential |
Low |
Foundations |
Soil |
Nid Height |
26 |
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.
South Fork
North Fork Powder River