Chart Shows Big Sioux River's Record-Breaking Flooding Spike

A chart from the National Weather Service (NWS) shows the astounding leap in water level at the Big Sioux River in Sioux City, Iowa, as slow-moving storms triggered devastating floods over the weekend.

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Nearly 2,000 properties in Iowa have been impacted from the heavy rainfall and life-threatening floods, with first responders making 250 water rescues, according to Iowa Governor Kim Reynolds. Up to 10 inches of rain fell in some areas, and the Big Sioux River ran so high near Sioux City that it caused the collapse of a railroad bridge after the span was submerged by the raging river on Sunday night.

The Big Sioux River is still running very high, NWS reported. A chart on the agency's website revealed the startling rise in the river's water level. According to the chart, the river climbed 25 feet in approximately 24 hours beginning on Saturday night, cresting around 45 feet on Sunday night, shattering its previous height record by more than 7 feet.

As of Monday afternoon, the NWS river gauge shows it still hovering around 45 feet. The previous record was 37.7 feet. NWS meteorologists anticipate the river level will slowly fall over the next few days, although the forecast shows it remaining above the record-breaking mark until early Friday morning. The river is expected to continue falling until it finally drops below action stage by Saturday.

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NWS meteorologist Dylan Dodson told Newsweek that the rainfall amounts were uncommon for the area, but that multiple other storm systems pose a threat for more rain in Iowa, arriving as soon as Monday night. Hopefully, Dodson added, the rain will fall north and east of the severely impacted regions.

Another storm will deliver the chance of rain during the day Tuesday, but that rain might fall in central and southern Iowa, again avoiding those areas experiencing the worst of the floods. A third system could drop more rain overnight on Thursday.

Photos shared across social media portray the stunning contrast between the river at normal levels compared to the impact of extreme flooding.

"Catastrophic flooding continues along the Big Sioux River near Sioux City with I-29 closed to the north! The river crested at 45 feet which is higher than ever before," extreme storm chaser Reed Timmer shared on X, formerly Twitter, with a video of the floods.

Timmer said Little Sioux River also flooded badly. Newsweek previously reported that in northwest Iowa, 13 rivers overflowed, submerging entire neighborhoods and at least one town.

Many flood warnings are still in place in southeastern South Dakota, southern Minnesota and northwestern Iowa, according to the NWS. In Iowa, several warnings are active until the weekend, with others issued until further notice.

"Turn around, don't drown when encountering flooded roads. Most flood deaths occur in vehicles," the NWS office in Des Moines said. "Be especially cautious at night when it is harder to recognize the dangers of flooding."