WATER: Does it always run downhill?
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TOPIC: WATER |
DO-GOODERS/THE ARTS
ENERGY
GOVERNMENT
LAND USE
PARKS/NATURE
HEALTH/CONSUMER
RECYCLING
WORK
TRANSPORTATION
WATER
POTRERO VIEW
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February 28, 2005
At 11 o’clock sharp, four days a week, Dolphin Club-member Lou Marcelli enters the frigid water at Aquatic Park along San Francisco’s northern waterfront for a 20-minute swim. He calls it “the lazy man’s way of working out.” Local residents with worries about water quality might call it just plain unsafe. Concerns about water quality don’t deter Marcelli and other intrepid water-lovers from the Dolphin Club or South End Rowing Club, athletic programs that have been encouraging people to swim in the San Francisco Bay since the 1870s. Aquatic Park was opened to the public in 1939 after the addition of the Hyde Street Pier in 1923 and the Municipal Pier in 1931 created a lagoon. But particularly because of the swimmers, both the San Francisco Public Utilities Commission (SFPUC) and Department of Public Health carefully watch for water quality problems. These public agencies sample 14 sites weekly in the bay and ocean, including two at Aquatic Park, for elevated bacteria levels, which indicate that disease-causing microorganisms may be lurking. They do additional monitoring when a combined sewer overflow (CSO) occurs, usually during heavy rains. Out-of-control sewage sounds pretty unsavory. Fortunately, it doesn’t happen often, and when it does occur, water quality often returns to normal within 72 hours, according to SFPUC. “By way of comparison, in the 1970s we had 200 discharges a year,” said Tyrone Jue, SFPUC public relations officer. “Now we’re down to approximately five per year citywide.” The public is notified immediately when there’s a water quality problem. “When a discharge actually happens, an alert goes out to our monitoring crew,” said Jue. “So their first action is to go out and leave the beach notices warning people of the potential risk of elevated bacteria levels…. The sample takes about 24 hours to correctly do analysis. If bacteria levels are found to be low, then we take down warnings.” Sewage overflows happen in part because San Francisco’s water treatment system is uniquely comprehensive. In the East Bay storm water runs directly into the bay, taking with it petroleum residues, pesticides, and other pollutants. Much (though not all) of San Francisco funnels its storm runoff through the sewer system, where it receives two treatments before being released into the bay or ocean. However, when the 465-million-gallon-a-day-capacity system is inundated by a big storm, the water must be released before being fully treated so sewage doesn’t flood the streets. “There’s the benefit of treating and removing pollutants,” said Kimia Mizany, policy manager at the nonprofit organization Save the Bay. “The problem it poses is when you have very heavy rain and the water overflows. You’re not just overflowing storm water, you’re also overflowing your sewage.” Water released into the bay or ocean during a CSO receives only primary treatment, which means the water has been “slowed down to the point where heavier solids in the water will settle out and lighter materials will float to the surface,” according to Tom Franza, SFPUC assistant general manager of wastewater enterprise. Surface material is skimmed and bottom material scraped for further processing. The secondary treatment the water would otherwise receive includes another step. “We use bacterial cultures to consume or breakdown the biodegradable material that remains in the water,” said Franza. “It’s very similar to what happens naturally in rivers and streams, but we provide optimal conditions so everything breaks down more quickly than it would in nature.” The water is then disinfected. However, even secondary processing doesn’t completely remove nonbacterial pollutants, including grease and oil, metals such as mercury and lead, and pesticides. And when a sewage overflow happens, greater concentrations of these substances hit the bay and ocean. Mike Kellogg, SFPUC supervising biologist, says the Commission monitors “a huge range of parameters in our effluent,” as part of state requirements. Some are measured daily, some monthly or quarterly. These measurements are separate from the bacteria-monitoring process that can result in public warnings about swimming safety. Lorraine Anderson, a Department of Public Health senior environmental health inspector for water quality, explains why: “If you were to swallow water that had a potential disease-causing agent [such as bacteria], you would get sick. Chemical contaminants are a concern for birds and fish because they live in the environment. They’re going to be affected by that. But people who swim, even if they swim on a daily basis, their exposure is very much reduced from what a plant or animal living in bay or ocean water would be exposed to.” Though there’s little health risks to swimmers associated with chemical contaminants, the “ick” factor, as well as the health of wildlife and plants, are issues. Individuals can help the environment and protect swimmers from pathogenic bacteria by keeping cars well maintained; recycling motor oil; disposing boat sewage in onshore facilities; wrapping pet waste and baby diapers in plastic bags and disposing of them properly; using compost instead of chemical fertilizers; not using pesticides; using nontoxic household products; planting landscapes rather than paving them; not washing paved surfaces with a hose; and reducing water use, especially during heavy rains. Kellogg also advised swimmers that “I would think that anyone who swam in the bay would want to inform themselves as much as possible.” To find current water quality: |
Steven Moss
Executive Director
steven@sfpower.org
San Francisco Community Power
2325 3rd Street, Suite 344 San Francisco, CA 94107
Phone: 415-626-8723 Fax: 415-626-8746