PHILADELPHIA (CBS) – The big problem in Philadelphia remains the potential for widespread flooding.

Mayor Nutter says all of the city’s waterways — the Schuylkill and Delaware Rivers, Cobbs Creek, Wissahickon Creek, Penny Pack Creek and Frankford Creek — are already above flood stage. The Schuylkill is expected to crest around 8pm at 15 feet — the highest level since 1869.

Other problems in the city include scattered power outages and downed trees. Numerous road closures remain in effect. The city’s 311 non-emergency call center remains open, and Nutter urges everyone to reserve 911 calls for life-threatening situations.

Overnight, 169 residents sought shelter at three high schools — Bartram, Lincoln and Roxborough — that opened as shelters. Four buildings in the city collapsed, with no serious injuries reported. Several apartment buildings were evacuated because of flooding or electrical problems.

The mayor on Saturday evening declared a state of emergency in the city, an action that enhances police powers to deal with people who insist on being out in unsafe conditions. It also helps the city claim potential federal disaster aid. It was the first such declaration in Philadelphia since 1986.

Reported by Mike Dunn, KYW Newsradio