Barricades were erected throughout Tiffin Saturday night as flood waters made their way onto city streets.
Mayor Aaron Montz said the sewer could not handle the water due to it coming up so fast.
"(The sewers are) at the max," he said.
Tiffin Police Department was checking the Sandusky River and Rock Creek every half an hour Saturday night.
As of about 10:30 p.m. Saturday, the viaduct on North Washington Street was flooded and closed, and Main Street near Heidelberg University's senior apartments was flooded. Rebecca Street was being closed, and Montz said people only were allowed out - not in.
He said the water was going to go up onto South River Road, and he said he was almost positive the water would go up into the Rebecca Street parking lot at Heidelberg. The university's security department was contacted about moving vehicles in the lot. He said he was not sure how they would get them moved due to winter break.
"The sand bags are already in place (at Tiffin Community YMCA)," he said.
Areas throughout Seneca County experiencing high water were CR 594; SR 587, north of TR 96; SR 231, south of CR 6; SR 4, north and south of Attica; North SR 53 at CR 32; SR 101 at CR 179; SR 19 at CR 32; and Euclid Avenue. Also, US 224, east of SR 100, was closed.
A flood warning for Sandusky River at Tiffin went into effect around 10 p.m. Saturday. At 9:45 p.m., it was at 7.1 feet, about 2 feet shy of flood stage, and moderate flooding was in the forecast.
Montz said he thought the 11.4-foot projected crest was scheduled for 9 p.m. today.
"It's not good. We're concerned," he said.
Montz said if it were to hit 12 feet, officials would have to start talking about getting people out of the Charlotte Street and Front Street area.