“A correction to an earlier version of this article has been appended to the end of the article.”
SAN JOSE — A day after rescuers boated hundreds of people to safety during San Jose’s worst flooding in decades, city officials Wednesday let many of the 14,000 evacuated residents return home and blamed the sudden overflow of Coyote Creek on bad information about its capacity.
The flooding followed a series of heavy rains that filled Anderson Reservoir to capacity. Downstream, Coyote Creek quickly swelled to four feet above flood level, cresting at 13.6 feet Tuesday and breaking a 95-year-old record of 12.8 feet set in 1922.
For many, the flooding came with no warning. Mayor Sam Liccardo acknowledged residents should not have first learned of the danger when rescuers arrived by boat to evacuate them. Hundreds remained displaced Wednesday, with the city and Red Cross offering two high schools that are closed for spring break as overnight shelters that drew about 275 people.
Officials have yet to begin assessing damage to the neighborhoods, where the city has already issued health warnings about the dangerously polluted floodwaters, and it may be weeks before life is back to normal for residents in some of the most badly damaged homes.
Liccardo said Wednesday that the city relied on information from the Santa Clara Valley Water District that Coyote Creek could handle 7,400 cubic feet per second in the Rock Springs area before it would flood surrounding homes. But that wasn’t the case: The maximum flow recorded by the water district was 7,428 cubic feet per second about 1 p.m. Tuesday — only slightly higher than the expected capacity, but well after flooding had begun.
“What we’re learning is the data’s wrong and we need to understand why that is,” Liccardo told this news organization following a news conference Wednesday. “Obviously that’s something we need to undertake in partnership with other agencies that have the experts. We don’t have the hydrologists. They do.”
Water district officials acknowledged the flooding happened at a lower flow rate than anticipated, but said the district uses the best information it has.
“It’s what our model could best predict based on available data,” said Rachael Gibson, the district’s emergency operations center spokeswoman. “And we cannot predict if there were blockages or other conditions that would modify capacity.”
Gibson said the district notified the city about 3 a.m. Tuesday of increased water flows at a metering station upstream from Rock Creek.
All that was little comfort to Jean-Marie White, 46, a San Jose resident who lost the entire lower level of his home — including three bedrooms and a family room. White was in the middle of remodeling the backyard of his 16th Street home.
“If we had some advance notice, we could have moved the furniture upstairs,” White said, adding that he got his information from a Yahoo! community group instead of official agencies. “I feel like the city and the water district could have done a better job notifying us.”
City officials Wednesday afternoon had no estimate of how many homes were actually flooded, the cost of the damage, how many were displaced or how soon they could return. They said 246 people were rescued by boat Tuesday. The Coyote Creek flooding also temporarily closed Highway 101 in Morgan Hill on Tuesday and North San Jose Wednesday morning.
Liccardo and the Silicon Valley Community Foundation established a “San Jose Flood Victims Relief Fund” to help raise money for those who were displaced. By Wednesday afternoon it had received $150,000, including $100,000 from the Silicon Valley Auto Dealers Association, $20,000 from the San Francisco 49ers and $10,000 from the California Water Service. PG&E offered to match up to $20,000, and the San Jose Earthquakes soccer team pledged to match the first $10,000 donated through its fundraising page.
City officials Wednesday were surveying flooded neighborhoods to assess the damage. Liccardo was joined by Councilman Tam Nguyen and Rep. Ro Khanna, D-San Jose.
Jan Null, meteorologist for the Golden Gate Weather Service, said that what a given channel can carry in one year may differ from what that same channel can carry in the next year.
“If the channel becomes smaller for some reason,” such as a pileup of brush, then “an 11-foot-high” event could “give you the equivalent of a 12-foot” high event, he said.
A buildup of silt and plant growth in the Guadalupe River up through the early 1990s resulted in that channel having its capacity cut by 40 percent. Since then, hundreds of millions of dollars in improvements have made it much more resistant to flooding. Gibson said Coyote Creek’s flooding was a clear example of why such improvements are needed on that corridor as well.
“This really underscores the importance of getting federal money for projects along major creeks like this,” she said. “You can see they’ve paid off elsewhere. We have pursued money for these purposes of flood protection in the past, but the government ultimately decided the benefit-to-cost ratio wasn’t great enough.”
San Jose fire Assistant Chief Robert Sapien said they’re preparing for more water that’s predicted to arrive over the weekend. They’re monitoring water levels, and continuing to drain Anderson Reservoir to try to keep it below overflow levels that could again exacerbate problems downstream.
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It wasn’t the first time Coyote Creek has flooded — those who have lived along the water recall the El Niño waters of 1997 as well as a deluge in 1983 that caused particularly devastating flooding farther downstream in Alviso.
Eric Heckman, who has lived in the William Street area for 14 years, said he noted where the water had reached in 1997 and later renovated his backyard to fortify it against that benchmark. That wasn’t enough for this week’s storm.
“The level then was knee-high, but you can see the water level this time was up to here,” he said gesturing to his chest. “That was never anticipated.”
Correction: Feb. 24, 2017
An earlier version of this article incorrectly stated that Coyote Creek crested at 14.4 feet around 3 p.m. Tuesday. It crested at 13.6 feet.
