Snowflake Reservoir Report
Nearby: Ethel #3 Margaret No.2
Last Updated: December 18, 2025
Snowflake is an earth dam located in Johnson, Wyoming, with a primary purpose of irrigation.
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Summary
Constructed in 2006, this private-owned structure stands at 40 feet tall and stretches 575 feet in length. With a storage capacity of 45 acre-feet, it serves multiple purposes including fire protection, stock, and small fish pond in addition to irrigation.
Situated on the Jasper Draw river, Snowflake has a low hazard potential and is classified as having a fair condition assessment as of August 2018. The dam features an uncontrolled spillway with a width of 30 feet and an outlet gate with a single valve. Despite being privately owned, the state of Wyoming regulates, inspects, and enforces compliance with regards to Snowflake, ensuring its safety and functionality for the surrounding area.
With a moderate risk assessment rating of 3, Snowflake has not had an Emergency Action Plan (EAP) prepared or updated recently. The dam undergoes inspections every 5 years, with the last assessment conducted in August 2018. Its location on County Road in Johnson, Wyoming, makes Snowflake a crucial water resource for irrigation and other related activities, contributing to the water management efforts in the region.
Year Completed |
2006 |
Dam Length |
575 |
Dam Height |
35 |
River Or Stream |
JASPER DRAW |
Primary Dam Type |
Earth |
Surface Area |
2.73 |
Hydraulic Height |
30 |
Drainage Area |
0.07 |
Nid Storage |
45 |
Structural Height |
40 |
Outlet Gates |
Valve - 1 |
Hazard Potential |
Low |
Foundations |
Rock, Soil |
Nid Height |
40 |
Seasonal Comparison
Weather Forecast
Nearby Streamflow Levels
Powder River At Arvada
|
243cfs |
Wild Horse Creek Near Arvada
|
0cfs |
Clear Creek Near Arvada
|
256cfs |
Piney Creek At Kearny
|
113cfs |
Clear Creek Near Buffalo
|
17cfs |
Powder River At Moorhead Mt
|
60cfs |
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.
Snowflake