In stormy winters like this, residents of drought-prone Southern California fret about how much rainfall flows into the ocean, a reminder of the amounts of water the region is wasting instead of saving for good use. A new bill by a San Fernando Valley state senator aims to fix that. The bill introduced Monday by Sens. Bob Hertzberg, D-Van Nuys, and Scott Wiener, D-San Francisco, would require huge reductions in the volume of treated wastewater discharged into the Pacific Ocean and California estuaries.