Officials say heavy rains sent about 9.6 million gallons of a mix of stormwater and sewer water into Baltimore streams last week.
The Baltimore City Department of Public Works said in a statement Wednesday that 7.5 million gallons flowed into the Jones Falls from locations on Preston Street and on Falls Road on Friday.
An additional 2.1 million gallons flowed into Herring Run from a stream bank manhole near Belair Road.
The Preston Street and Falls Road locations are structured overflows that are located underground and do not spill onto city streets. Structured overflows were designed as part of Baltimore’s sewer system more than 100 years ago to alleviate excess volume in the wastewater system when storm water infiltrates into the sewer mains. The structures automatically divert excess water directly into streams to prevent it from surfacing on streets or in basements.
Officials say it was the second time in a week that discharges occurred in this pattern as a result of rainfall.