Raw sewage has leaked from the Bay Area's sewer systems into waterways more than 100 times since heavy rainfall began drenching the region after Christmas.
Heavy rains can overwhelm the system, forcing the infrastructure to release the excess water, including waste. Utility officials say that the spills are mainly rainwater with small amounts of sewage.
"Even when we're seeing these unauthorized discharges, it's primarily stormwater mixed in with a very small percentage of wastewater," said Eileen White/, a director with the San Francisco Bay Water Board.
A New Year's Eve storm was particularly heavy. EBMUD, which serves the East Bay, said its intake went from 50 million gallons on average to 650 million gallons that day.
The spills have been also blamed on aging pipes which have been bent and broken by shifting soils, earthquakes and other factors.