Revitalizing California’s floodplains benefits people and wildlife

a landscape of a river with green trees on the banks

While the Sacramento River can be calm, it is also known to breach levees, flooding nearby towns. Credit: Cindy Sandoval/USFWS

By Meghan Snow
April 20, 2021

Throughout California’s history, rivers have been diverted, rerouted and contained by concrete. While these actions have brought agriculture and communities to arid land, and reduced large-scale flooding, it has also eliminated some of the natural benefits provided by untamed rivers. Today, efforts are underway to restore some of the natural riparian areas to the benefit of both humans and wildlife.

a field with newly planted vegetation

State, federal, city and county agencies and private organizations came together to build setback levees on the outside perimeter of the orchards, and native tree saplings were planted where fruit trees used to grow. Credit: U.S. Army Corps of Engineers

“Over the past few decades, the Sacramento Valley has seen a lot of riparian restoration projects,” said Jennifer Hobbs, a senior wildlife biologist at the U.S. Fish and Wildlife Service’s Sacramento office who oversees consultations on federal water projects. “These projects are targeting areas where the agricultural and development value is low due to flood risk, but connectivity between wildlife areas is high.”

Small, riverside communities are often on the frontlines battling breached levees, and some are choosing to restore floodplains instead of repairing aging levees. For many years, Hamilton City, a small community in Northern California, experienced widespread flooding from the Sacramento River breaching the old levee that was built in the early 1900s. In fact, residents were evacuated six times between 1980 and 2000. The city determined the failing levee was too expensive to maintain and turned to nature for a solution.

In partnership with the Army Corps of Engineers, Reclamation District 2140, the California State Department of Water Resources, River Partners and The Nature Conservancy, more than 1,400 acres of orchards adjacent to the levee were purchased and fallowed.

a sign that says "area beyond this sign closed. All public entry prohibited."

A U.S. Fish and Wildlife Service sign at the Sacramento National Wildlife Refuge separates public-restricted wetlands between the Sacramento River and private orchards in Hamilton City, California. The new setback levees pass directly between these wetlands and the orchards. Credit: Todd Plain/U.S. Army Corps of Engineers

Smaller levees, known as setback levees, were built along the outside perimeter of the land, and native tree saplings were planted where fruit trees used to grow. The main levees along the river were removed, and a floodplain was born. Now, when heavy rains raise the river, the floodplain absorbs the river overflow instead of inundating the town with muddy water.

“This was one of the first projects that combined flood control and ecosystem restoration to secure federal funding to help move the project forward,” said Hobbs.

Today, the land is transforming into a natural riparian floodplain and upland grassland habitat. Close to Sacramento National Wildlife Refuge and Llano Seco Wildlife Area, the floodplain expands the natural area that wildlife can roam.

“This particular piece of land is great for listed species like the western yellow-billed cuckoo. They need large, contiguous patches of land for breeding, so efforts like these are important to help their numbers recover,” said Hobbs.

The floodplain also benefits other wildlife, including valley elderberry longhorn beetle, deer, ringtails and bats, as well as aquatic species, like salmon, which spawn in the shallow gravel edges of the river.

“When you use floodplains to provide protection for agriculture and people’s homes, you also provide wildlife habitat,” explained Hobbs. “And when you have a healthier river, you’re setting up a future that can better weather the effects of climate change.”

a coyote in a field

Connected open spaces give wildlife, like this coyote seen at the Sacramento National Wildlife Refuge, corridors to roam and move safely. Credit: John Heil/USFWS

Some river restoration projects start with wildlife in mind but provide benefits for humans downstream. Along the Kern River, the Southern Sierra Research Station is working with the Audubon Society to enhance 49 acres of riparian habitat historically used by western yellow-billed cuckoo and southwestern willow flycatcher, also a listed species under the Endangered Species Act. The research station is replanting willow and cottonwood trees, along with native plants and shrubs like milkweed, to attract a wide variety of birds, insects, and other wildlife species to the property.

a bird in a tree

River habitat restoration projects benefit the western distinct population segment of the yellow-billed cuckoo by providing more nesting habitat, which is important for the recovery of the species. Credit: Peter Pearsall/USFWS

“Most riparian species like a changing landscape consisting of old and new vegetation,” said Amber Aguilera, a senior wildlife biologist at the Service’s Sacramento office who focuses on species recovery. “The variation creates more habitat for insects, which the birds eat and feed to their young.”

The Kern River restoration project also includes removal of non-native plants which can change the hydrology of the riparian area. Non-native plants can consume more water and have root systems that are a detriment for the longevity of the riparian floodplain.

“When you restore riparian habitat, you improve the stability of the waterway,” said Aguilera. “Native vegetation can reduce erosion and sediment input into the river, improving downstream water quality.”

That’s good news for people who depend on the Kern River for drinking water. While the river water is treated before human consumption, reduced sediment loads going into the treatment plants means better quality water going into homes.

a landscape shot of a field with hills in the background

The Kern River restoration project includes removal of non-native plants which can consume more water and have root systems that are not good for the longevity of the riparian floodplain. Photo courtesy of John Stanek/Southern Sierra Research Station

“Having healthy waterways and water sources are incredibly important for humans and wildlife,” said Aguilera. “Thankfully, there are a lot of really dedicated partners making sure riparian restoration happens in the right places to maximize benefits for everyone.”

With weather patterns and water supplies becoming more and more unpredictable in the Golden State, riparian and floodplain restoration can help many communities looking to improve water quality and protect residents and businesses from flooding. And the wildlife will be happy, too.


Story Photo

Meghan Snow

About the writer...

Meghan Snow is the public affairs officer for the Sacramento Fish and Wildlife Office. An avid biker, runner and snowboarder, she brings her love for the outdoors to the office every day, promoting the Service's conservation work throughout the region.

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