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Leave it to Beavers

Once considered a pesky rodent, the animals are busy saving California’s salmon populations.

Photo: Márcio Cabral de Moura

This story was produced by the Food and Environment Reporting Network, an independent, nonprofit news organization focusing on food, agriculture, and environmental health.

In an unexpected twist to California’s drought saga, it turns out that beavers, once reviled as a nuisance, could help ease the water woes that sometimes pit the state’s environmentalists and fishermen against its farmers.

In California, where commercial and recreational salmon fishing brings in $1.5 billion a year, and agriculture earns $42.6 billion annually, farmers and fishermen have long warred over freshwater from the Klamath and Sacramento rivers. Dams built for reservoirs on these rivers have cut off many salmon from their breeding areas, which has severely depleted the populations. Typically, up to 80 percent of the diverted water is used by agriculture, much of it sent to the arid Central Valley region where moisture-demanding crops like almonds are now being intensively farmed.

In the ongoing drought, however, both sides of this conflict are suffering. Authorities have cut water supplies to agriculture, forcing farmers to abandon crops or drill wells and buy surplus water at ever-steeper prices. Meanwhile, fishery experts predict the worst for Chinook and Coho salmon.

Only 5 percent of the Sacramento River winter-run Chinook salmon survived this year, according to a recent report from the California Department of Fish and Wildlife. This would mean very few wild adult Chinook salmon would return to the rivers in three to four years, making hatchery fish the species’ only hope. In 2008 and 2009, California officials shut down Chinook salmon-fishing entirely, leaving not just fishermen adrift, but chefs and consumers without a favorite summer food.

While Coho salmon runs are healthy in places like Alaska, California does not allow commercial or sportfishing of the species due to its critically low numbers. It’s believed that only 1 percent of the historical population still exists in the state. Some fear the drought may push California’s endangered Coho salmon all the way to extinction.

Salmon spend their first one to two years in freshwater before heading to the sea. They return as adults to lay eggs. During these times, they require cold, slow water and protective covering, which coastal rainforests in California once provided. Heavy logging in the late 19th century destroyed much of this habitat, which was then converted into farms, vineyards, and residential areas.

Beavers, which were almost hunted to extinction in California during the 1800s, can help restore this watery habitat, especially in drought conditions. Fishery experts once believed the animals’ dams blocked salmon from returning to their streams, so it was common practice to rip them out. But, consistent with previous studies, research led by Michael M. Pollock, an ecosystems analyst with the National Oceanic and Atmospheric Administration, shows the opposite: Wild salmon are adept at crossing the beavers’ blockages.

In addition, the dams often reduce the downstream transport of egg-suffocating silt to the gravel where salmon spawn, and create deeper, cooler water for juvenile fish and adult salmon and steelhead. The resulting wetlands also attract more insects for salmon to eat. In ongoing research that covered six years, Pollock and his colleagues showed that river restoration projects that featured beaver dams more than doubled their production of salmon.

Can the animals help bring back the Coho salmon? “Absolutely,” Pollock says. “They may be the only thing that can.”

Not far from the Oregon border, the Mid Klamath Watershed Council (MKWC) is collaborating with the Karuk and Yurok tribes to create a beaver-centered river restoration plan on tribal and public lands. “Beavers are the single most important factor in determining whether Coho salmon persist in California,” MKWC executive director Will Harling says. “They work night and day, don’t need to be paid, and are incredible engineers.”

What’s more, Pollock’s work shows that by slowing a river’s flow and allowing water to soak into the ground, beaver dams can raise the water table under the land. “So they don’t just help fishermen,” he says, “but can help ranchers and farmers save on water pumping and irrigation costs.”

Because of water shortages, the Scott River Watershed Council (part of the Klamath River system) has been working with U.S. Fish and Wildlife Services and the California Department of Fish and Wildlife to encourage beavers to do their thing. Early findings show that wells behind beaver dams have recharged significantly faster than those on land without them.

Garreth Plank, a cattle rancher on the Scott River, has always welcomed the animals to his land. As a result, he has found that the beavers save the ranch significant amounts of money each year. “One of our largest expenses is electricity for pumping water,” Plank says. “With beavers on the land, the water tables are higher, and we’ve had a 10 percent to 15 percent reduction in pumping costs.” Along with saving money, Plank now boasts 76,000 Coho fingerling (very young fish) and 35,000 Chinook fingerling in his property’s rivers.

Jim Morris, a Scott Valley rancher at Bryan-Morris Ranch, says he tried to get rid of beavers for years. “But they do slow the water from leaving the valley and enhance water tables,” he says. “Due to their benefits, we started planting more trees, and instead of calling it riparian and shade plantings, we call it ‘beaver food.’ ”

But California Department of Fish and Wildlife environmental scientist Matthew Meshriy says North America’s largest rodent is still often unwelcome in the state’s agricultural areas, particularly the Central Valley, where their dams can interfere with the complicated water infrastructure vital to farms. “If we had a more natural system and grew things appropriate to the land and at an intensity level that was sustainable for the long term,” says Meshriy, ”then a beaver could be a powerful part of it. But that’s not the case here.”

Despite such resistance, beavers are enjoying a comeback in California, even building dams in downtown San Jose, Martinez, and Napa. And interest is increasing elsewhere: Pollock has been hosting standing-room-only workshops on the benefits of beavers in salmon watersheds all along the West Coast.

“Fishermen welcome beaver dams much more than the human-built dams on salmon streams,” says Zeke Grader, executive director of the Pacific Coast Federation of Fishermen’s Associations. “If beavers are allowed to do their jobs, they'll help the fishermen keep salmon on the plates." 

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Allan Harris