The combination of a deep snowpack, a liquid equivalent exceeding 4 inches, and frozen soils due to persistently below-normal spring temperatures set the stage for flooding along the Big Sioux. However, a significant rise in temperatures, well above normal, triggered rapid snowmelt. The resulting runoff swiftly made its way into the Big Sioux River and its associated tributaries.
The Big Sioux river headwaters near Florence set a record flood stage. Points downstream along the Big Sioux River crested at moderate to major flood stage. Many local and county roads and bridges were impacted by the high water, along with widespread inundation of agricultural lands.
A Presidential Disaster Declaration was approved for Brown, Clark, Codington, Day, Faulk, Grant, Hand, Marshall, Potter and Roberts Counties, as well as for the Lake Traverse Indian Reservation, where an estimated $2,305,362 in total qualifying costs were incurred during spring flooding.
Apart from the mainstem river, there was heightened concern regarding Lake Kampeska. The Watertown Water Filtration plant and numerous local residences faced threats from both elevated lake water levels and the potential for ice breakup and shoves. In response, residents initiated sandbagging operations to safeguard their properties.

Flood in CODINGTON, SOUTH DAKOTA
From 09-APR-23 16:45:00 to 30-APR-23 23:59:00 (CST-6)
Location: WATERTOWN
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Pelican Lake levels to rose above flood stage on April 15th. The lake peaked at a level of 1713.6 on the afternoon of April 20th.

Flood in CODINGTON, SOUTH DAKOTA
From 12-APR-23 01:45:00 to 24-APR-23 05:45:00 (CST-6)
Location: RAUVILLE
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The Big Sioux river gauge in Watertown at Sioux Conifer Road peaked on the afternoon of April 12th at 10.9 which is moderate flood stage. This only affected pasture land in the area.

Flood in CODINGTON, SOUTH DAKOTA
From 12-APR-23 03:45:00 to 18-APR-23 11:30:00 (CST-6)
Location: (ATY)WATERTOWN ARPT
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Big Sioux River gauge at Lake Kampeska peaked just below moderate flood stage at 21.93 feet.

Flood in CODINGTON, SOUTH DAKOTA
From 12-APR-23 01:15:00 to 13-APR-23 23:45:00 (CST-6)
Location: APPLEBY
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Big Sioux river below Watertown peaked at major flood stage with a crest of 12.12 feet. This mainly impacted agricultural lands, though the water was high enough to reach the bridge at 177th Street on the south end of Watertown.

Flood in GRANT, SOUTH DAKOTA
From 11-APR-23 20:00:00 to 16-APR-23 08:30:00 (CST-6)
Location: HILAND
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Big Sioux river near Florence peaked in major flood stage at 9.58 feet in the early morning hours of April 13th. This is a record flood stage for this location. Being the headwaters of the Big Sioux the main impacts were to local and county roads and bridges as well as agricultural lands.

Flood in CODINGTON, SOUTH DAKOTA
From 11-APR-23 21:00:00 to 15-APR-23 17:15:00 (CST-6)
Location: FLORENCE
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The Big Sioux river near Watertown peaked at 11.81 feet in moderate flood stage on the morning of April 13th, however only agricultural lands are impacted at this level.

Flood in HAMLIN, SOUTH DAKOTA
From 09-APR-23 21:00:00 to 30-APR-23 23:59:00 (CST-6)
Location: APPLEBY
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The Big Sioux river near Castlewood crested at 11.65 feet, well into moderate flood stage. This overtopped a road in addition to flooding agricultural lands.

Flood in CODINGTON, SOUTH DAKOTA
From 12-APR-23 02:45:00 to 27-APR-23 13:45:00 (CST-6)
Location: (ATY)WATERTOWN ARPT
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The Big Sioux River gauge at Broadway Ave in Watertown crested in moderate flood stage at 11.26 feet in the evening of April 20th. Lower banks were topped and low lying areas flooded.

Flood in CODINGTON, SOUTH DAKOTA
From 11-APR-23 09:45:00 to 13-APR-23 10:45:00 (CST-6)
Location: RAUVILLE
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Mud Creek near Rauville peaked at 10.46 feet, 1.46 feet above flood stage.

Flood in CODINGTON, SOUTH DAKOTA
From 11-APR-23 15:15:00 to 12-APR-23 09:15:00 (CST-6)
Location: RAUVILLE
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

The South Branch Tributary Mud Creek near Rauville crested at 4.54 feet. The main impact was inundation of agricultural lands.

Flood in CODINGTON, SOUTH DAKOTA
From 11-APR-23 12:00:00 to 12-APR-23 15:30:00 (CST-6)
Location: RAUVILLE
Flood cause: Heavy Rain / Snow Melt
Property damage: 0.00K
Crop damage: 0.00K
Reported by: River/Stream Gage

Willow Creek near Watertown hit flood stage in the early afternoon of April 11th, increasing to 15.90 feet later during the overnight hours. This is 5.9 feet above flood stage and mainly affected agricultural lands.