… Atmospheric rivers almost guarantee one thing for San Francisco: millions of gallons of stormwater and raw sewage will get poured into the Pacific Ocean and San Francisco Bay. In San Francisco, sewage and stormwater flow through the same pipes as part of a combined system. The problem is that large enough storms cause the system to overflow, which the city said typically happens less than 10 times a year. … Environmental groups and the state of California argue that the city is discharging too frequently and at such high volumes that it taints the waterways with bacteria that can cause illness if people come into contact with it.

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