After record flooding in parts of western Iowa in 2019, officials with the U.S. Army Corps of Engineers are predicting below-normal runoff into the Missouri River system during the year ahead.
Kevin Grode, an engineer in the Corps’ Omaha office, compared last year’s runoff with this year’s prediction. “The 2020 calendar year runoff summation for the Missouri basin above Sioux City, Iowa, was 31.1-million acre-feet, 121% of average,” Grode says, “The 2021 calendar year runoff forecast is 23.1-million acre-feet or 90% of average.”
Some sections of western Iowa are ranked as being in moderate, severe, or extreme drought. Grode says the soil is very dry and there isn’t much snowpack across the basin.
“The below-average runoff forecast for 2021 reflects current drier-than-normal soil moisture throughout the basin and below-average plains and mountain snow,” Grode says. “We are expecting below-average runoff during the high runoff period from March through July when the plains and mountain snow melts.”
Grode says the mountain snowpack is also below normal so far. “Mountain snowpack is accumulating at below-average rates in both regions, above Fort Peck and Fort Peck to Garrison,” Grode says. “It is important to note that the majority of the mountain snowfall typically falls between January 1 and mid-April.”
The below-normal forecast follows several years of above-normal-to-record runoff in the basin.
(By Jerry Oster, WNAX, Yankton)