Not an endless summer for beaches’ bluffs and cliffs

Researchers are learning more about how waves and precipitation are carving Ocean Beach in San Francisco — as well as the San Mateo County coast — findings that could be used to guide emergency tactics in the near future.

Due to tectonic activity on the San Andreas Fault, the bluffs and cliffs lining the coast from Pacifica to Pescadero are being lifted at a rate of approximately a meter every 1,000 years, said Bruce Richmond, who studies coastal erosion for the U.S. Geological Survey.

“It doesn’t sound like a lot, but it’s significant,” Richmond said.

That phenomenon, coupled with sea levels rising at approximately a meter every 100 years, continues shaping new formations into the coast and changing some of the area’s most popular beaches, albeit slowly, Richmond said.

The integrity of coastal bluffs, popular recreation spots, is thus reduced.

Beaches are typically full of sand in the summer, when storms and tides aren’t drawing them into the ocean. Once the rain sets in, the amount of sand on the beaches decreases greatly and the bluffs really take a beating, Richmond said.

Brian Collins, a coastal and marine geology researcher for USGS in Menlo Park, has been studying how waves affect the coast.One of his most important findings shows that watching wave patterns and technology can help predict when, where and how waves are going to hit the coast, Collins said. These predictions are especially relevant to Pacifica, where tsunami alarm systems are being installed and more attention is being focused on how to watch out for landslides in the future.

Supervisor Rich Gordon said his office has not looked at the issue of coastal erosion in great depth since the Local Coastal Plan, which guides coastal development, was revised two years ago. But he said coastal erosion, particularly as it relates to safety, is something the county’s planning department has kept an eye on.

San Francisco, San Mateo County beaches earn top marks

Nearly all the beaches in San Francisco and San Mateo Counties earned “A” grades for cleanliness this summer in a statewide report released recently.

Water quality at California beaches was excellent, according to nonprofit group Heal the Bay’s 2007 California Summer Beach Report Card.

The report is based on routine monitoring of beaches conducted by government health agencies, which includes analysis of bacteria, such as fecal waste. The higher the grade, the lower the risk of illness to beachgoers, according to Heal the Bay.

Of the 20 monitored locations in San Mateo County, 19 — or 95 percent — received A’s. Pillar Point Harbor in Half Moon Bay received the only “B” grade this year, according to the report. As with previous years, there were no known sewage spills that led to beach closures in the county this summer.

San Francisco earned similar marks — all 14 regularly sampled monitoring locations, including Baker Beach east, China Beach, Ocean Beach and Sunnydale Cove at Candlestick Point, received “A” grades. There were no sewage spills or sewage overflows that resulted in closures in The City, either.

tramroop@examiner.com

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