SACRAMENTO, Calif. -- With picturesque rolling hills, plenty of good eats and a reputation for producing world-class wines, it’s no wonder why nearly three million visitors flocked to California’s Napa Valley last year. But for local residents and businesses, the region has another reputation—a reputation for flooding.
“The history of flooding in Napa is that they have experienced major flooding every five to 10 years,” said Floyd Bolton, area resident engineer for the Corps. “In 1986, they experienced a major flood event which flooded 60 percent of the city.”
The 1986 flood was one of the region’s most devastating, resulting in mass evacuations, homes destroyed and more than 100 million dollars in damage.
Today, the U.S. Army Corps of Engineers and the Napa Flood Control and Water Conservation District are wrapping up more than 13 years of work that changes the way water moves through the city - restoring natural flood plains and wetlands, and helping to prevent flooding in downtown Napa. The project has also re-connected downtown Napa with its riverfront with a new floodwall that provides pedestrian access to shops, restaurants and a community park along the river.
This year, the Corps’ budget provided $16.6 million for the project’s final phase: a new dry bypass that will create a shortcut for the Napa River to help reduce the risk of flooding.
“The oxbow is kind of a u-shape in the river, and during a flood event the water wants to take the shortest path so it will go over the banks and try to cut through the oxbow,” Bolton said. “What the oxbow bypass does is it allows the water to go where it wants to go anyway.”
Design on the oxbow dry bypass is complete, and a construction contract is expected to be awarded later this year.
In May, construction wrapped up on two box culverts, essentially tunnels large enough for a car to drive through, that will provide a shortcut from Napa Creek to the Napa River, helping keep high water out of neighboring homes and businesses.
“The main feature of the project is to install two bypass culverts that allow water to flow into them during a flood event,” Bolton said.
The improvements along Napa Creek quickly paid dividends last winter when the creek passed heavy rains without flooding.
Life-long Napa resident Gaylen Walters, who has seen numerous floods since moving to the area in 1955, said he couldn’t believe how well it worked.
“I thought that it was going to come up onto the street and flood us and it just stopped even though it kept raining,” Walters said.
Just downstream of Napa Creek, work to replace a railroad bridge over the Napa River wrapped up in August 2012.
The Napa River bridge was raised by up to 10 feet because it was too low, catching debris in the river and causing flooding. The Corps also installed a new concrete bridge over the future oxbow bypass and shifted about 2,500 feet of railroad track to align with the new bridges.
While the work’s not done yet, local residents like Gaylen have seen the project’s benefits, and can imagine a drier future for downtown Napa.
“I’ve seen it work, and it looks like it’s going to really help us out,” Walters said.