MILL VALLEY, Calif. (AP) " The investigation into last week's 2.7-million gallon sewage spill into San Francisco Bay has revealed another massive spill at the same Marin County treatment plant six days earlier.
State water officials say last week's spill of partially treated sewage was preceded by the release of about 2.5 million gallons of virtually raw sewage during a storm on Jan. 25.
The Sewerage Agency of Southern Marin reported the first spill to the state Regional Water Quality Control board, which oversees the water treatment plant in Mill Valley.
But the Marin agency did not report how much sewage was released and used an incorrect date.
The regional water board is investigating both spills, but the board may also be investigated.
Linda Adams, who heads the state Environmental Protection Agency, wants an independent review of the regional water board because it failed to immediately investigate the first sewage spill.
Altogether, more than five million gallons of sewage was released into a creek that flows into Richardson Bay, an arm of San Francisco Bay between Sausalito and Tiburon.