Guerneville floods more than anywhere in the Bay Area. Why can’t it be fixed?

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It is a scenario familiar to Northern California residents: A wet winter arrives with heavy storms, and Guerneville, the picturesque Sonoma County town 75 miles north of San Francisco, is hit with flooding.

Since 1940, the Russian River has poured over its banks at Guerneville a stunning 38 times, an average of nearly once every other year.

Why can't the river be fixed and the misery ended for people who live nearby? Building a dam or other major flood control project would be prohibitively expensive for a town of just 4,500 people, experts say. And federal law doesn't allow tax money to be spent on large water projects whose benefits are worth far less than the costs of the project.

In other words, if a dam costs $1 billion, but the houses it would protect are worth only $200 million, the Army Corps of Engineers won't approve the project. And the few hundred homes in Guerneville aren't worth enough money to make a large project pencil out. That's why most major flood projects, like those for the Guadalupe River in San Jose or the Sacramento River in Sacramento, are in heavily populated areas.

"They would be competing nationally for limited funds," said Grant Davis, general manager of the Sonoma County Water Agency. "You need to hit that cost-benefit ratio and I don't think that's going to happen."

A big dam would also permanently change the scenic Russian River area, with its vineyards and tourism industry, and would undoubtedly be met with years of lawsuits.

The most cost-effective solution, the experts say, is probably to continue a program, started more than 20 years ago, that uses federal funding to raise up hundreds of houses in town, allowing flood waters to pass by and do relatively little damage when they inevitably arrive.

Guerneville is situated in the redwood canyons of the Coast Range, "and there's nothing you can do if you are in a canyon like that," said Jeffrey Mount, a veteran river expert and professor emeritus of earth sciences at UC-Davis.

He added, "Put up a monster dam? Who is going to pay for that? It's easily a billion dollars. It also would flood the Russian River, which is a major recreation area, with vineyards all around.

"The best you can do is tear down those houses or elevate them," Mount said.

This year's flooding was especially bad. A slow-moving atmospheric river storm dumped a foot of rain in the Guerneville area in the 48 hours between Monday and Wednesday. Five miles north, in the hamlet of Venado, 20 inches fell in two days. Amid the monsoon-like deluge, the river level quickly rose 13 feet over flood stage to 45 feet, its highest level in 24 years.

By Thursday morning, news reports showed residents rowing boats down main streets, National Guard troops at work, and propane tanks, portable toilets and massive trees floating down the roaring, muddy river.

"In an already saturated environment, there's nowhere for the water to go," said Davis. "Sonoma took the brunt of this. Twenty inches of rain is just amazing."

Guerneville's founders did not do their great-grandchildren any favors.

The town began in the 1850s as a lumber camp. It was started by loggers, lured to the misty groves of ancient redwood trees that grew all around. With oxen, axes and long saws, they cut so heavily through the enormous trees that the area became known as "Stumptown." By the 1860s, a young Swiss immigrant named George Guerne opened what became the area's largest sawmill, and the town's name changed to Guerneville.

With the Russian River so close, the loggers could easily float huge redwoods downriver to sawmills. But they also built Guerneville in the river's flood plain.

By the late 1800s, when the railroads came, the town became a popular vacation spot for Bay Area residents, who built vacation cabins. But, as with other former Northern California redwood logging towns, like Boulder Creek and Mill Valley, those summer cabins eventually became permanent housing.

Guerneville, which now has 4,500 residents and hosts popular summer festivals, flooded badly in 1940, 1964, 1997, 1986 and 2006.

Part of the reason is the unusual route of the Russian River.

Most rivers start in mountainous areas and spread into wide flood plains near the places where they empty into the ocean, said Mount, who is now a senior fellow at the Public Policy Institute of California, a nonprofit think tank in San Francisco.

But the Russian River, named for 1820s Russian explorer Ivan Kuskov, does just the opposite.

It begins in Mendocino County and flows 110 miles south through Sonoma County to the ocean, where it empties near Jenner. Along the way, the river flows through wide-open areas and some of America's greatest wine-growing regions.

Geologists believe that millions of years ago, the river flowed directly into what is now San Francisco Bay, or perhaps the Central Valley. But earthquakes, and the rising and falling of the landscape over millennia, made the Russian River take an odd right turn near Healdsburg, as the ground shifted under it.

Instead of emptying gently into San Francisco Bay, it now roars through the precipitous canyons of the Coast Range, past Guerneville, causing it to rise and fall with shocking speed. Sonoma's coastal hills receive roughly 60 inches of rain a year on average -- four times as much as San Jose, Fresno or Los Angeles and amounting to billions of gallons of water.

"Everything that comes down that valley, all the way from Ukiah, has to go to the ocean," Mount said. "The river is flowing through narrow gorges. And when you have to stuff all that water through a narrow gorge, there's just not enough width in the channel. So the river rises very fast. And there's nowhere for it to go but out."

Two large dams farther upriver, which form Lake Mendocino and Lake Sonoma, provide drinking water for 600,000 people in the two counties. They limit some flooding, but only catch about 18 percent of the watershed's annual rainfall.

But building another dam would be too expensive, Mount, Davis and other experts say. And, with Guerneville's small population, the project would not meet the cost-benefit test. The Russian river is also full of endangered salmon and steelhead trout, and local residents would be likely to fight submerging vineyards and other property, or even building large concrete flood walls. Instead, Sonoma County began a program in 1995 to pay 75 percent of the cost of raising homes in Guerneville and other areas at risk of flooding.

Funded with more than $12 million so far, most of it from FEMA, the Federal Emergency Management Agency, the program provides up to $39,000 per home. Homeowners raise their first floor to 10 feet or more off the ground, and must sign deed restrictions agreeing to use the bottom level only for a garage or storage. They also must obtain flood insurance.

Roughly 250 homes in Guerneville have been elevated in the past 20 years, and about 200 more are still in need.

"The program saves lives and reduces the cost of repairs in areas with repetitive flood risk like Sonoma County," said FEMA spokeswoman Brandi Richard.

Why does anyone live in Guerneville with so much risk? The same reason people live on the San Andreas or Hayward Fault, or in fire-prone areas, or in hurricane-threatened communities like Miami or New Orleans, said Mount. Because it's beautiful.

"The odds of a significant earthquake are high, but we go on," he said. "In Guerneville, eventually you get flooded. The trade-off is to live in a beautiful place, next to this river, knowing you could be flooded."

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