Flooding continues on a river in South Dakota nearly a year after it was first triggered by heavy rain and snowmelt from a Plains bomb cyclone last March.

Six river gauges on the James River in eastern South Dakota have been above flood stage for 300 or more days. Mitchell leads the way with 320 days above flood stage, or since March 14 of last year, which is when the bomb cyclone brought disastrous flooding to parts of the Plains.

All six locations have set a record for flood longevity. It's the first time in the past 40 years this many river gauges have remained above flood stage for 300 days or more, according to the Missouri Basin River Forecast Center.

Forestburg and Mitchell have crushed their longest-lasting floods of record set in 2011 by 149 days and 87 days, respectively.

The James River flows into the Missouri River at the border between Nebraska and South Dakota. From there, its waters head into the Mississippi River and eventually the Gulf of Mexico.

Most of the current flooding on the James River is confined to low-lying and/or rural and agricultural areas, but the flooding could worsen heading into spring.

There is a 50% or greater chance of major flooding on the James River at some point through April, according to a long-term flood risk outlook from NOAA. One factor in that forecast is the significant snowpack across the river's drainage basin.

Rain and melting snowpack is how this long-duration flooding got its start last March.

The Dakotas had their wettest year on record in 2019, which has allowed this river flooding to persist into the start of 2020.

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