REDWOOD CITY -- Winston Bumpus stood on the redwood deck of the Sequoia Yacht Club on Tuesday morning, training a careful eye on the murky green water just a couple feet below.
The club's New Year's Eve party wouldn't start until 8 p.m., but he'd arrived about 12 hours early at the Redwood City marina to make sure the morning's high tide didn't sneak over the deck and into the club's carpeted interior. He had sandbags and plastic sheeting ready, but in the end they weren't needed: The water got within 1.5 feet of the deck before retreating around 10 a.m.
"We knew the weather was going to be good, so that was a big sigh of relief," said Bumpus, the club's 62-year-old commodore. "A bad storm and some strong wind and this would've been a different story."
The highest tides of the year, known as king tides, are flowing back into the Bay Area this week. Thanks to Northern California's unseasonably dry and sunny weather, the higher than normal water levels are not expected to cause any serious flooding in low-lying areas. But they provide fresh opportunities to glimpse what the region's shorelines will look like in coming decades.
King tides happen several times a year, caused by the Earth's position relative to the sun and moon. It's a natural phenomenon that's occurred for eons, but recently a coalition of government agencies and environmental groups have begun using the seasonal fluctuation to illustrate the local challenges posed by global climate change.
The California King Tides Initiative encourages citizens to explore and photograph king tides in their area. The idea is to make the looming but abstract threat of sea-level rise more tangible as well as document areas that will be most impacted this century, when the National Academy of Sciences predicts coastal California's oceans will rise by more than 5 feet.
This week the king tides were expected to peak Tuesday and Wednesday. In Redwood City, the high tide at 11:41 a.m. Wednesday was forecast to be 9.6 feet above the average low tide mark, according Logan Johnson, a meteorologist with the National Weather Service. That's 1.39 feet above the mean high tide level for Redwood City.
By themselves, king tides aren't dangerous. But when winter storms and high tides combine, water surges inland from the bay and ocean. Marc Holmes, a program director for the Bay Institute, said that sort of flooding is going to worsen as the planet warms, threatening buildings and facilities on the shoreline and shutting down low-lying freeways such as Highway 101 and Interstate 880.
"The impact of storms coinciding with sea-level rise," said Holmes, whose organization works to preserve the San Francisco Bay watershed, "is what's going to damage our infrastructure and economy."
For San Francisco Baykeeper, a watchdog group whose lawsuits have forced Bay Area cities to spend tens of millions of dollars upgrading sewer systems, the worry is that rising sea levels will inundate pipes that drain stormwater and treated wastewater into the bay, causing backups and sewage overflows during heavy showers. Holmes claimed these backups will have another effect: greater and more frequent flooding of residential neighborhoods as rain-swollen rivers and creeks top their banks.
State and local officials are beginning to grapple with the consequences of sea-level rise. Last month, for instance, Assemblyman Rich Gordon and San Mateo County Supervisor Dave Pine helped convene a half-day conference on the outlook for the county, which has nearly 58 miles of coastline.
And like other entities that occupy the bay front, including Silicon Valley titans like Facebook, the Sequoia Yacht Club faces some hard decisions in coming years about its facilities.
"The tides keep rising, so we need to look at it and figure out what we're going to do," said Bumpus, "because at some point this is not going to be a viable location, or we'll need to raise the building."
To view photos of king tides in your area, or to find out where to go to see them, visit www.californiakingtides.org.