MODESTO, Calif. (AP) — Between sprawling almond orchards and dairy pastures in the heart of…

MODESTO, Calif. (AP) — Between sprawling almond orchards and dairy pastures in the heart of California’s farmland sits a property being redesigned to look like it did 150 years ago, before the levees do restrict the flow of rivers that cross the landscape.

The 2,100 acres (1,100 hectares) at the confluence of the Tuolumne and San Joaquin rivers in the state’s Central Valley are becoming a floodplain. This means that when heavy rains cause rivers to overflow, the water runs off the land, allowing traditional ecosystems to thrive and reducing the risk of flooding downstream.

The Dos Rios Ranch Preserve is California’s largest floodplain restoration project, part of the nation’s larger effort to redesign river flow as climate change alters the environment. The land it covers was once a farm, but the owners sold it to the nonprofit River Partners for use in restoring wildlife habitat.

The state wants to fund and prioritize similar projects that reduce risk to homes and property while providing other benefits, such as enhanced habitats, improved water quality, and potential groundwater recharge. depleted groundwater. By slashing or removing levees, swollen rivers can flow over land that no longer needs to be kept dry.

“It gives new life ecologically but in a way that is consistent and complementary with the human systems that have developed over the 150 years since the gold rush,” said Julie Renter, president of Rivers Partners.

The Central Valley covers approximately 20,000 square miles (51,800 square kilometers) and is an agricultural powerhouse – over 250 crops are grown there. The region accounts for about 1% of US farmland, but produces 25% of the nation’s food while accounting for one-fifth of all groundwater pumping in the United States.

A flood in the 1860s demonstrates the potential for disaster; up to 6,000 square miles (15,500 square kilometers) of the valley were submerged. As the state’s population grew rapidly and agriculture boomed in the 20th century, the government designed extensive systems to move water to supply people and farms, and erected levees to protect cities and cultures.

Some of these levees cut off rivers from their natural floodplains. As climate change leads to warming temperatures, mountain snow that typically flows into the state’s watershed can fill rivers much faster, increasing flows beyond what levees can handle.

Floodplain restoration can help. For projects like Dos Rios, land that farmers no longer want to manage is transformed into space where rivers can breathe. Further north, barriers on the Feather River have been modified to allow more water to flow into an existing wildlife area. In West Sacramento, 4 miles (6.4 kilometers) of levee along the Sacramento River is receding.

California authorities began centralizing valley flood planning ten years ago. Although some of the worst and most notable flooding in decades has occurred in places like Houston and New Orleans, parts of California are at serious risk that is only expected to increase due to climate change. . In 1997, major storms caused levees to burst throughout the valley, including on the Tuolumne River, causing nearly $2 billion in damage and destroying more than 20,000 homes. Nine people died.

An update to the Central Valley Flood Protection Plan is expected to be released this week. It will detail ways to reduce flood risk and protect the estimated 1.3 million people who live in floodplains, as well as key infrastructure, farmland and ecosystems.

In the last update five years ago, the state gave a bounty to floodplain restoration projects. Dos Rios is one of 17 listed by the state. Four have been completed since 2013, three are under construction and 10 are proposed. They’ve cost $300 million so far, with the money coming from bond funds and local and federal dollars.

“Dos Rios is an amazing example, but we need 30 more,” said Jane Dolan, chair of the Central Valley Flood Protection Board.

Floodplain restoration is not unique to California. Washington State launched a program in 2013 called Floodplains by Design, and projects are springing up along the Mississippi River. But experts say California stands out for its focus on projects that provide ecological support.

“There’s tremendous potential for this type of work, and I’m quite impressed with how deliberate and thoughtful California is in this space,” said Todd Bridges, Army Corps Engineering with Nature program manager, who takes a similar approach.

The Biden administration has set aside at least $1.75 billion on the infrastructure bill for multipurpose projects aimed at reducing flood risk.

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Just as climate change is making California’s dry spells drier, it is expected to make the wet spells wetter. The state experienced an atmospheric river in October and heavy rain and snowfall in December, followed by its driest January to March on record.

“One of the things that drives me crazy about California water is that policy makers want to talk about floods in flood years and droughts in drought years,” said Barry Nelson, a water consultant who has worked on the Dos Rios project. “The weather boost we’re seeing this year really teaches us that we need to break out of this pattern.”

Since the 1850s, 95% of historic wetlands and riverine habitats in the Central Valley have been eliminated, according to state flood planners. It would be impossible to restore all of that in a state of 40 million people, where major cities like the capital Sacramento and Stockton have been built on flood plains.

But the vast open spaces of the valley provide opportunities, such as on farmland that is no longer in use. The property Dos Rios sits on was more recently a dairy, and the owners approached River Partners to sell the land for conservation purposes in the mid-2000s.

River Partners has notched berms to allow river water to flow over 1,000 acres (400 hectares). The nonprofit navigates government barriers to cross a federal levee that keeps the Tuolumne River at bay. Eventually, Dos Rios could hold up to 10,000 acre-feet of floodwater, preventing it from flowing to towns like Stockton. An acre-foot is approximately 325,850 gallons (about 1.23 million liters).

Fourteen types of trees and woody shrubs are planted to attract native species. River Partners said the available habitat at Dos Rios allowed the Aleutian Cackling Goose to be removed from the endangered species list. River rabbit, chinook salmon, rainbow trout, yellow warbler, and sandhill crane are among the species that inhabit Dos Rios.

Proponents of such projects would like to see them built faster in California and beyond. Renter, of River Partners, said while there is broad agreement on the value of floodplain restoration, concerns about the impact of land conversion on local tax bases and debates over how expanding public access can slow things down.

But in the messy world of California water, floodplain restoration stands out, said Nelson, the water consultant.

“In this kind of ocean of disagreements on water policy, on all these other issues, flood management is that place where huge changes have happened over the last decade in a way that is incredibly widely supported,” he said.

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