But over the past 50 years, some places have occasionally run afoul of the act. In San Francisco, the wastewater system discharges a mix of sewage and stormwater into the bay during major storms, often causing bacteria levels to exceed EPA regulatory standards .

The Supreme Court has made it harder for environmental regulators to limit water pollution, ruling for San Francisco in a case about the discharge of raw sewage that sometimes occurs during heavy rain

The Supreme Court's conservative majority ruled for San Francisco in limiting the power of environmental regulators to prevent ocean discharges of polluted stormwater.