The California State Office of Emergency Services reports that the 2.7 million gallon sewage spill happened sometime between 5:30 and 8:30 pm Thursday night in Richardson Bay. How the spill occurred is still being determined.
Sanitation officials said none of the spill contained chlorine used to treat sewage and the communities of Mill Valley, Sausalito, Tiburon and Belvedere were notified of the spill.
The extent of the spill's spread into the Bay is unknown but there have been no reports of wildlife affected by the spill, Pittman said.
The public is being advised not to come in contact with the water, Pittman said.
Bay City News contributed to this report.