Hurricane Irene did more than topple trees and turn out the lights across the Baltimore area. The storm left behind some nasty, stinky reminders of its fury, as sewage spills forced beach closures and triggered warnings to stay away from the water as summer draws to a close.

The worst problem came in the Baltimore Highlands area southwest of the city, where a ruptured sewer main has poured about 100 million gallons of raw sewage into the lower Patapsco River over the past week. Power outages also led to more than a dozen other sewage spills across the region.

And even as workers pushed to repair the Baltimore Highlands main, environmentalists warned that more spills are likely because the region's sewage infrastructure is old, leaky and inadequate.

"Until we fix those pipes or back up those power supplies, until we make those investments, why wouldn't we keep seeing these things whenever we have a storm or a power outage or another natural disaster?" asked Jenn Aiosa, senior scientist with the Chesapeake Bay Foundation.

A neighbor of the Patapsco Pumping Station on Old Annapolis Road reported the Baltimore Highlands spill soon after it occurred around midnight Saturday, officials said. Baltimore County hired a contractor to replace the broken 54-inch concrete pipe and another smaller pipe that was found to be damaged.

The larger pipe pumps about 17 million gallons daily to the Patapsco Wastewater Treatment Plant in Baltimore — all of which has been pouring into the river while workers replace the damaged line.

Donna Miller, who has lived near the pumping station for 40 years, said she's grown used to getting a whiff of sewage, but "the smell is much worse this week." Besides the odor, she's had to put up with "a lot of noise and bright lights all night" as the contractor, Spiniello Companies Inc., worked around the clock on repairs.

"There was no good solution to this problem," said David Fidler, spokesman for Baltimore County's Department of Public Works. "The line had to be repaired immediately. Letting sewage spill into the river, while we repaired the line, was the only thing we could do. Otherwise, it would back up into homes."

Workers were expected to complete repairs Friday night or early Saturday, and the cost for the week-long repair is estimated at $500,000.

Signs have been posted along the river warning residents to avoid the water, and Anne Arundel County's health department issued a warning covering the downstream stretch of the Patapsco as well. Health inspectors are monitoring the water quality daily, Fidler said, and have found that the water is unsafe to swim or wade in — or even to touch.

Another 16.5 million gallons spilled into other Baltimore County rivers, creeks and coves, including the Jones Falls and Gunpowder River, from a dozen sewage pumping stations that lost power during the storm. The stations were back in operation within a day or two, but Fidler said county repair crews couldn't get to them right away because of safety concerns about downed trees and power lines.

Health officials sampled the county's four officially sanctioned swimming beaches and a few other locations downstream of the overflows, and did not find water-quality problems in most areas. But they closed the beach in the Hammerman Area of Gunpowder State Park because of elevated bacteria in the water.

After closing the Patapsco in Brooklyn, Anne Arundel health officials issued a blanket warning late Wednesday that all of the county's waters may have unsafe levels of bacteria in the wake of the storm. They urged residents to avoid swimming, wading or touching any water through Saturday.

Baltimore, which is frequently troubled by sewage overflows, experienced some during the hurricane as well, but none greater than 10,000 gallons, according to public works spokesman Kurt Kocher.

Meanwhile, on Friday, Harford County officials disclosed that a sewage overflow last weekend spilled 263,000 gallons of raw or partially treated waste, some or all of which "may have reached the Bush River," according to the county's public works department. The state Department of the Environment was notified, as required by law, county officials said, and signs were posted at the time along the waterways affected by the spill.

About 20 sewage overflows, pumping station failures and other spills have been reported statewide, but there could be more, according to Dawn Stoltzfus, spokeswoman for the Maryland Department of the Environment.

Though extensive, the storm-driven spills are unlikely to cause serious or lasting environmental harm, experts say. The waste is diluted and breaks down as it's flushed by storm-swollen streams and rivers into the Chesapeake Bay.

But in the short term, the sewage spi;;s in the Baltimore area are likely to worsen water quality in what's already the most degraded portion of the bay, says William C. Dennison, vice president for science applications at the University of Maryland Center for Environmental Science. The Patapsco and Back rivers earned a failing grade on the university's most recent bay health report card, and have consistently scored poorly over the years.

Dennison said organic matter in the untreated sewage will consume dissolved oxygen in the water as it breaks down, aggravating the rivers' existing low-oxygen problems.