Flash Flood — La Salle, Illinois

2021-07-12 to 2021-07-13 · near Seneca, La Salle, Illinois

Event narrative

A slow moving thunderstorm produced torrential rain and flash flooding across portions of eastern La Salle County including in Seneca. Vegetation was flattened near many creeks and channels due to the fast moving flood waters. Along Hog Run, vegetation was flattened near North 21st Road with debris near the road. Along North 2350th Road near Armstrong Run, flood waters flowed over the roadway with debris in the channel. North La Salle Road was flooded, just south of Dupont Road with debris piled on the side of the road along with erosion in the channel. There was substantial deposition of sediment from a nearby sand and gravel facility across Dupont Road near Deadly Run. A substantial stretch of Dupont Road was flooded with extensive mud marking on pavement, east of Route 170 near a marina. Just west of Route 170, the east abutment to the River Road bridge over a small creek was washed out. A local highway department staff member was driving over this area when the washout occurred. His truck became stuck on remaining pavement on either side of the washout. The driver needed to be rescued and refused medical treatment. Scouring occurred on both sides of the creek with vegetation collapsed or partially collapsed. Homes on Timmons Lane were flooded with one home suffering a basement wall collapse. Further west near River Road and Lake Street, flooding of several houses occurred as Spring Brook Creek overflowed with water flowing over fields and into the houses. Significant damage occurred to vegetation where Spring Brook Creek crossed River Road. Rainfall of 4.24 inches was reported during a 3 hour period, one mile east of Seneca. The damage amount was estimated in consultation with local emergency management officials.

Wider weather episode

Scattered thunderstorms moved across portions of central Illinois during the afternoon and evening of July 12th. One storm moved very slowly over eastern La Salle and western Grundy Counties. Torrential rain produced flash flooding in these areas with numerous roads flooded and at least four bridges damaged.

View location on OpenStreetMap → (41.3478, -88.5924)

Source: NOAA Storm Events Database, event_id 970361. Narrative written by the NWS forecast office that issued the report.