Preventive measures deter flooding

When it was all said and done, last week's much-anticipated series of storms brought nearly five inches of rain to Petaluma, along with some downed trees and debris, but no significant flooding.

"Things went well," said Public Works Director Dan St. John, reflecting on how the city fared between Thursday, Nov. 29, when rains started falling, and Sunday, when they finally let up. During that time, crews spread out across town to address some localized flooding.

The area that seemed most impacted, St. John said, was along Industrial Drive, where on Friday morning some parking lots were starting to hold water.

Lee Fishman, owner of Fishman Supply, found his parking lot in particularly deep water that day. Thankfully, he said, it didn't affect his business much, though in the past such flooding has made it "near impossible" for him to operate.

Fishman says his parking lot has flooded every year now for the last five or six years, which he attributes to water being displaced from the $40-million plus flood project downstream that has successfully alleviated flooding in the Payran area. That project is about 95 percent complete, with only a few manmade obstructions in the river needing to be removed before it is considered finished.

But flooding such as Fishman experienced can't be attributed to just one cause, said Ted Cabral, who chairs the south county's Flood Control Advisory Committee. "There's no single thing that causes flooding in Petaluma," he added. "There's a number of ingredients -it's like baking a flood pie." He listed "ingredients" like tides, the amount of rain, and how clear the waterways are, among other things.

Still, Petaluma has completed one terracing project across from Petaluma Valley Athletic Club to address flooding in the Industrial Drive area, he said. Another terracing project on land adjacent to Fishman's property will start sometime next year and should help mitigate the flooding there.

Cabral and St. John attributed the general lack of flooding in Petaluma to a range of factors. One was environmental: The ground was not yet saturated from previous rains and the storms were spaced out, allowing water to subside.

Another was city staff vigilantly clearing debris, particularly fallen leaves, out of storm drains.

But Cabral said another big factor was the city and county water agency's heightened efforts to clear silt and debris from waterways.

Before last year, he said, it was very difficult to get the numerous environmental permits required to clear a stream - but then the water agency found a way to simplify the process.

This has allowed county crews this year to remove massive amounts of silt, invasive plants, and large items left in streambeds by the homeless, such as mattresses. Such objects can create mini-dams when they get snagged on branches.

The results are clear, Cabral said, when comparing how Petaluma and Penngrove weathered the storms. While Petaluma "didn't come close to flooding," Penngrove, where not as many streams had been cleared, was under water in some areas.

"There's never going to be a cure for flooding, so we have to find ways to somehow manage it, and the efforts we've made recently are big improvements," he said.

(Contact Jamie Hansen at jamie.hansen@arguscourier.com)