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Website in the Works to Predict Palo Alto, Calif., Flooding

The website would display the San Francisquito Creek on a map and use a color-coded system to indicate the likelihood of it overtopping at known trouble spots.

(TNS) -- A new website is in the works that could give neighbors of San Francisquito Creek nearly two hours advance notice of a flood.

"We want to create a system that is easily understandable in a short period of time for both the public and emergency response community," Len Materman, executive director of the San Francisquito Creek Joint Powers Authority, said at a Board of Directors meeting Thursday.

The flood-prone creek flows out of the Santa Cruz Mountains and through the cities of Palo Alto, Menlo Park and East Palo Alto on its way to San Francisco Bay. It last overtopped its banks on Dec. 23, 2012, damaging several homes and businesses in East Palo Alto.

The website would display the creek on a map and use a color-coded system to indicate the likelihood of it overtopping at known trouble spots, Materman said. Red would mean that flooding is expected, yellow that flooding is possible and green that everything is OK.

The warnings would be based primarily on data collected by a newly integrated system of U.S. Geological Survey and Stanford University flow gauges positioned upstream of the Pope-Chaucer Street Bridge. The span, which joins Palo Alto and Menlo Park, is one of several chokepoints along the creek and the location where major flooding occurred in 1998.

The website would offer an hour and 45 minutes advance notice of flooding, Materman said. That's a significant improvement over the 45 minutes provided by the USGS flow gauge alone.

"I don't want to sit on that data and not tell people," Materman said in an interview after the meeting. "We want the public and the emergency response community to know so that they can take actions."

In addition to flow gauges, seven rain gauges that were installed throughout the watershed earlier this year will provide insight into the impact of rainfall on creek flows, Materman said. There are also plans to add ground saturation sensors in the coming months.

A storm that walloped the Bay Area last week provided a good opportunity to test out the system, Materman said.

There were failures. For example, a flow gauge on Los Trancos Creek, a tributary of San Francisquito Creek, stopped transmitting data when a phone line went down. And the USGS flow gauge, which is used to calibrate the others, wasn't transmitting data often enough.

"It's a work in progress," Materman said. "There were deficiencies. There probably will still be as we continue to iron this out."

The upper watershed recorded 5.2 to 6.3 inches of rain between Dec. 10 and Dec. 12, said Materman. That's on par with a storm that caused the flooding in 2012. The difference this time was that the ground was not fully saturated. The creek approached but never exceeded 50 percent capacity.

There is no deadline to roll out the website, but Materman said he is shooting for the end of January. He estimated the total cost at between $125,000 and $150,000, which is being funded by the JPA, Palo Alto and a grant that Palo Alto is administering on behalf of the JPA.

The website and its color-coded system received a hearty thumbs-up from Portola Valley resident Jerry Hearn.

"I really like this approach," he said. "Those are the things people respond to."

Palo Alto Councilman Pat Burt, who sits on the JPA's Board of Directors, said the website isn't intended to replace one that displays the depth of the creek at Waverley Street, Chaucer Street and West Bayshore Road.

"The creek monitor tells us that we've hit the crisis," Burt said. "This is about anticipating it."

©2014 the Palo Alto Daily News (Menlo Park, Calif.)