The Schuylkill is expected to crest Sunday night at fifteen feet -- a level we haven't seen in more than 140 years, according to Philadelphia Mayor Michael Nutter.
"That is historically significant," said Nutter. "We have not seen that level of cresting since 1869."
The 1869 flooding was caused by the "Saxby Gale" hurricane on October 4. The Federal Emergency Management Agency named it a 100 year flood for the Schuylkill.
In his 10 p.m. briefing Saturday night, Mayor Nutter said he fully expect the creeks, river and streams will flood.
The Schuylkill Floods Over Its Banks
"The Schuylkill Expressway is experiencing flooding as well as in the Cobbs Creek area and a number of streets in the city," Nutter said.
Severe flooding remains the biggest threat to the region from Hurricane Irene and the worst of the storm was expected overnight and into Sunday morning.
Irene spawned a tornado south of Lewes, Delaware that demolished one home and destroyed more than a dozen others.
Power outage reports were coming in as the storm made its way up the east coast. In Northeast Philadelphia, power lines fell on a car, killing one of the people inside and sending the other to the hospital.