With the threat of rain this week, our area will once again be reminded that we aren’t in the clear when it comes to flooding.
David Pearson, senior service hydrologist with the National Weather Service (NWS) in Valley, said the flooding threat isn’t going away anytime soon.
OPPD environmental affairs administrator, Patrick Finigan, said this year, much like 2011 – another year of historic flooding – the Missouri River will require close monitoring. The fact that the river is already high, combined with above-average snowpack levels in the mountain states, could cause more flooding if it melts too fast.
“In general, the rivers are still running high, everything is elevated,” Pearson said. “It won’t take much for the Missouri River to get back into flood stage and cause problems.”
Pearson said the snowpack has begun to melt and will continue to do so until July. The latest models show the snowmelt will not be quick, which is good news.
The water release from Gavins Point Dam in Yankton, S.D., which feeds into the Missouri River, is at 55,000 cubic feet per second (cfs), compared to an average release of 20,000 cfs.
Last month, the dam released water at a sustained rate of 56,000 to 57,000 cfs. At times, the releases were as high as 90,000 cfs at the height of the flooding. Unlike 2011, the rivers and tributaries, especially the Platte and Elkhorn rivers, flooded at an unprecedented level. The floodwaters breached levees, destroyed dams and highways and caused millions of dollars in damages around the region. Heavy March rains quickly melted the snow cover. Frost that had not yet released from the ground caused massive water runoff that couldn’t soak into the soil.
OPPD personnel from across the utility worked around the clock to ensure infrastructure was protected and safe from encroaching floodwaters. Crews performed disconnections in evacuated areas – at the request of emergency management agencies – and reconnections in other areas.
Pearson said the tributaries and rivers between Omaha and Gavins Point are all fuller than normal and feeding into the Missouri River. Since those waters are joining the river below the dam, there is no way to control or hold that water back. But their flows could have a big impact on the Missouri.
If there is more flooding, it will be the Missiour River, not the Platte or Elkhorn rivers, that cause damage.
All that water flowing into the Missouri is measuring at just over 100,000 cfs at the Omaha measuring point. Pearson said normally, the Missouri River would be about 35,000 cfs in that spot.
What’s in store
Over the last few weeks, the river level has lowered, thanks to what has been, so far, a drier than normal April. But, Pearson said, the recent dry run is probably ending.
“The forecast right now isn’t encouraging,” he said. “We have the potential for rains this week and beyond, even into May.”
The heavier rains appear to be south of the Omaha area, into Kansas and Missouri. But the system could shift, and Pearson said if we do get heavy rains, and if they start releasing more water at Gavins Point, we will have Missouri River flooding.
“Our best case scenario is avoiding heavy rains and just battling through this and getting into the summer months, which are typically drier,” Pearson said. “People are on edge and want the river to get low again and start rebuilding. It won’t take much to cause more flooding. We are going to be watching this indefinetly.”