Plains snowmelt caused the Oahe Dam Reservoir pool at Pierre to go up almost a foot in the past day and it’s expected to keep rising for the next few weeks.
As of this (Thurs.) morning, the Oahe Reservoir elevation is at 1611.8 feet. Flood stage is 1620. Inflows are 150,000 cfs while outflows are 4,300 cfs. The reservoir is at 32.6 percent of its flood storage capacity.
As a comparison, the Oahe Reservoir rose to 1618.7 feet mean sea level in 1995 and 96. It reached a peak of 1619.7 feet msl in 2011 (June 26, 2011), and rose to 1617.2 feet msl in July of last year (July 31, 2018).
The US Army Corps of Engineers expects rapid rises in the upper Missouri River Dam System reservoir pools as the plains and mountain snowpacks melt and flow into the River. But, the Corps says the system has room to hold the runoff– barring a major rain event.
The Garrison Dam near Riverdale, ND, and the Oahe Dam at Pierre, SD, are the two biggest reservoirs along the upper Missouri River Dam System having nearly 50-million acre feet of combined water storage. The Corps is using them to hold the mountain and plains snowmelt so as not to exacerbate flooding along the river in southeastern South Dakota and points further south.
Find updated reservoir levels at http://www.nwd-mr.usace.army.mil/rcc/reports/pdfs/MRBWM_River_Daily.pdf.
