Baltimore's public works department said that a power outage at a wastewater treatment facility caused about 20,000 gallons of sewage to flow into the outer harbor on Saturday. The main power and backup power were disabled from 4:55 p.m. to 5:35 p.m., and 40,000 gallons of sewage flowed from the Patapsco Wastewater Treatment Plant, near Curtis Bay. Half of the spillage stayed on the plant site, while the rest entered the storm drain system and the outer harbor. The spill was caused by a power outage — possibly due to Saturday's storms — and a circuit interruption to backup power, according to the Department of Public Works. The agency is investigating the spill. —Gus G. Sentementes