Beach Report Card - California Coastkeeper Alliance

Background information on theSan FranciscoPublic UtilitiesCommissionThe city and county of San Francisco have a uniquestorm water infrastructure that occurs in no otherCalifornia coastal county – a combined sewer andstorm drain system (CSS). This system providestreatment to most of San Francisco’s stormwaterflows. All street runoff during dry weather receivesfull secondary treatment and all storm flow receivesat least the wet weather equivalent of primarytreatment, while most storm flows receivefull secondary treatment before being dischargedthrough a designated outfall.During heavy rain events, the CSS can dischargecombined treated urban runoff and sewage wastewater, typically comprised of 94% treated stormwaterand 6% treated sanitary flow. In an effort toreduce the number of combined sewer discharges(CSDs), San Francisco has built a system of undergroundstorage, transport and treatment boxes tohandle major rain events. CSDs are legally, quantitativelyand qualitatively distinct from raw sewagespills that occur in communities with separatesewers.In addition to most CSS stormwater discharges beingtreated, they are also of much shorter durationand lower volume than discharges in communitieswith separate storm drain systems. Because of theCSS, San Francisco’s ocean shoreline has no flowingstorm drains in dry weather throughout theyear, and therefore is not subject to AB411 monitoringrequirements. However, the city does havea year-round program that monitors beaches eachweek. Although most of San Francisco is served bythe CSS, there are some areas of federally ownedland and areas operated by the Port of San Franciscothat have separate storm drains.FIGURES 4-18 and 4-19Percentage of Grades by Time Period for San Francisco Bay Area(incl. San Francisco, Contra Costa, Alameda, Marin and San Mateo counties)GREATER BAY AREA: OCEAN SIDE511515105562 2AB411: April-October (42 locations)WINTER-DRY (18 locations)5DRY WEATHER (20 locations)590838565WET WEATHER (20 locations)KEY:GREATER BAY AREA: BAY SIDE1914551914431019873AB411: April-October (26 locations)1429WINTER-DRY (7 locations)57DRY WEATHER (21 locations)24WET WEATHER (21 locations)Numbers in BOLD indicate percentages143350