Minor flooding from melting snow in the northern Black Hills and foothills is possible this spring according to the National Weather Service’s Hydrologic Outlook. The rest of western South Dakota and northeastern Wyoming has little potential for snowmelt flooding. Minor flooding would cause minimal or no property damage and some inconvenience to landowners along the streams.
As of February 26, snow cover and liquid water content in the Black Hills and Bear Lodge Mountains were above average. Across the plains of northeastern Wyoming, snow cover was two inches or less. Snow depth across northwestern South Dakota is between four and 12 inches with higher amounts near the North Dakota border. Across southwestern and south central South Dakota, snow cover was less than an inch.
Above normal snowfall, heavy rain, or rapid snow melt would increase the flood potential, while below normal precipitation and gradually warming temperatures would decrease the magnitude of the current assessment. The Climate Prediction Center outlook through May indicates equal chances of normal, above normal, or below temperatures and precipitation for the Black Hills region.
The United States Bureau of Reclamation expects the Belle Fourche Reservoir to fill this spring and will discontinue inflows into the reservoir from the diversion canal in mid March, resulting in higher water levels along the Belle Fourche River downstream from the diversion canal.
If above average inflow into Pactola Reservoir from melting snow continues, additional water will be released from the dam and higher flows along Rapid Creek are possible.
Additional details can be found in the Hydrologic Outlook bulletin and the Advanced Hydrologic Prediction System web page.