Paul Chinn / The Chronicle
A flock of birds flies over the Yolo Bypass near Woodland, where conservationists hope to restore ancient floodplains.
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View All Images (5)Woodland, Yolo County —
Five acres of mud and rice stubble doesn’t look much like fish habitat, but the rectangular patch of summertime cropland is in the process of being converted to a teeming marsh filled with young salmon.
The conversion to wetland of the rice paddy at Knaggs Ranch, north of Woodland next to the Yolo Bypass, is an experiment that conservationists hope will eventually lead to the restoration of ancient floodplains all along the Sacramento and San Joaquin River corridors.
The small piece of soon-to-be-flooded cropland is an attempt to combine agriculture with habitat restoration, flood prevention with the creation of more floodplain.
“There is a real push to just build levees higher and bigger rather than really taking into account ecosystem functions,” said Jacob Katz, a biologist with the Center for Watershed Sciences at UC Davis. “We are hoping to say, ‘Look, this is how you do it. You can protect against flooding this way, too.’ ”
Breaching levees
The experiment, which involves the breaching of levees protecting the lower 5 acres of a 1,700-acre rice farm, is one example of the kind of innovation that conservationists hope will be inspired by California’s first ever attempt to create a systemwide plan to manage floods.
The $4.9 billion FloodSAFE initiative, which was created by the Central Valley Flood Protection Act in 2006, involves an ambitious program to increase public safety, promote long-term economic stability and improve environmental stewardship in the areas that have historically flooded during winter rains.
The state Department of Water Resources will issue a draft of its flood protection plan on Dec. 30, to be followed by a public comment period and hearings. The Central Valley Flood Protection Board, a panel of experts appointed by the Legislature, will have until July 1, 2012, to adopt the plan.
Salmon and rice
The document will set guidelines for flood protection and funding along the Sacramento River and around the Yolo Bypass, which was built almost a century ago as a relief valve for Sacramento River flood water. The specific programs will be developed by local and regional governments and communities.
The Knaggs Ranch study is being conducted by UC Davis, the state Department of Water Resources and rice paddy owner John Brennan, with support from Cal Trout and Trout Unlimited.
The plan is to trap the floodwater over the next month and, on Feb. 1, introduce 10,000 to 20,000 juvenile chinook salmon captured from the Feather River. Marshland habitat, including native grasses, is being restored inside the 5-acre plot.
Biologists will study the fish, waterfowl and nutrients in the water to determine the health of the wetland and to see how well the rice straw breaks down. One concern, Katz said, is that too much rotting rice straw could suck the oxygen out of the water and kill the fish.
Testing the waters
The researchers want to determine the right biological mix and, in collaboration with the owner, expand the off-season wetlands project to cover the entire 1,700 acres.
The hope, assuming all goes well, is that access points would eventually be designed so that migrating salmon in the Sacramento River could enter restored floodplains throughout the 59,000 acres of agricultural land in the Yolo Bypass and elsewhere along the Sacramento-San Joaquin River Delta.
It is important because the delta, built to funnel water through the 1,300-square-mile confluence of the Sacramento and San Joaquin rivers, is the heart of California’s vast water network. The system of levees, dams, channels and pumps funnels snowmelt from the Sierra Nevada to 25 million people in the Bay Area, Central Valley and Southern California.
The network was designed not just to provide drinking water, but also to prevent the kind of epic flooding that once occurred regularly in the Central Valley. Flooding was so bad in the winter of 1861-62 that the entire Central Valley became a vast lake.
Flooded rice farms
The Yolo Bypass was approved in 1917 as an outlet for floodwaters every couple of years when the Sacramento River overtops what is known as the Fremont Weir. The land beneath the bypass, which is reserved for agriculture during the summer, becomes an inland sea during heavy flooding.
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Migratory waterfowl regularly visit the flooded rice farms and a small area of restored wetlands called the Yolo Bypass Wildlife Area. Sometimes juvenile salmon spill over the weir into the bypass, but the area is not designed for fish, which often become trapped, when the water subsides, and die in evaporating pools.
Staggering fish migration
It is one of many reasons fisheries biologists believe California’s once vast population of chinook salmon has been declining despite an enormous yearly infusion of hatchery-raised fish. Only about 5 percent of the original Sacramento floodplains still exist, Katz said.
The creation of a statewide flood management plan is an opportunity to restore the floodplains where migrating fish historically rested, foraged for food and fattened up before returning to the river, Katz said. It would also stagger the migration over the course of the winter and spring season.
“Floodplains are important for foraging fish and for creating a more diverse portfolio of life histories,” Katz said. “By taking away floodplains and channeling them into rivers, we have taken that diversity away.”
The original idea behind the FloodSAFE initiative was to shore up the system of levees in the delta, which have failed 166 times over the past 100 years. The danger of flooding is now worse than ever, according to experts, who point out that the sea level is rising and land in the Central Valley is subsiding.
The state’s flood management plan, which could cost as much as $16 billion to fully implement, is expected to include a major expansion of the Yolo Bypass.
“By expanding the bypass we open the door for increased ecosystem restoration while getting the dual benefit of reducing flood risk,” said Michael Mierzwa, the supervising engineer and flood policy adviser for the Department of Water Resources. “The caveat that I put on that is that it is going to take decades to implement.”
Commitment in spotlight
The level of commitment to ecosystem restoration is the major concern among many environmentalists. Many local community leaders are vehemently opposed to converting farmland into wetlands. One big reason, Mierzwa said, is because both the agricultural land and the product grown on it are taxable. When you take a rice farm out of production, he said, you reduce the tax revenues which are, in turn, used to maintain the flood system.
The Knaggs Ranch experiment, Katz said, is designed to show how floodplain and habitat restoration can be accomplished without taking agricultural land out of production.
“We’re really talking about a paradigm shift in the way we push water around the landscape,” Katz said. “It’s going to be much cheaper to invest in a system that incorporates floodplain restoration now than it will be in the future. It will be better for ducks, better for fish and better for farms.”
E-mail Peter Fimrite at pfimrite@sfchronicle.com.
This article appeared on page A – 1 of the San Francisco Chronicle
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