Little Sioux Flood Stage Change

River channel modification, and the creation of a secondary
channel near the stream gauge location, during the 2019 flood
season has resulted in the previously documented flood stages no
longer remaining valid. A combination of recent in-person river
surveys, LiDAR analysis, archived satellite imagery, impacts from
recent flood events and coordination with local officials have
concluded that lowering the Action and Minor stages is needed. At
the same time, a slight raise to the Moderate and Major categories
would better align the categories with the noted impacts from
recent floods. Below are the new category levels:

Little Sioux River at Linn Grove
Previous Action Stage: 17.0 ftNew Action Stage: 14.0 ft
Previous Minor Stage: 18.0 ft New Minor Stage: 16.5 ft
Previous Moderate Stage: 19.5 ftNew Moderate Stage: 20.0 ft
Previous Major Stage: 21.0 ft New Major Stage: 22.5 ft

River forecasts will continue to be issued at and above Action
Stage, and Flood Warnings (FLW) will continue to be issued for
observed or forecast levels at or above Minor Stage. In both
cases, these values have been lowered over the previous values.

This change will be effective September 24, 2024.

If you have any questions or comments, please contact:

Andrew Kalin
National Weather Service Sioux Falls, SD
26 Weather Lane
Sioux Falls, SD 57104
605-330-4247
andrew.kalin@noaa.gov