Dams be damned: California rebuilds the salmon habitat it destroyed

Monica Heger, YES! Magazine, for TRUTHOUT

A consequence of the creek being confined to its channel is that, over years, the water has dug away at the creek bed — or substrate — making it deeper and narrower, and increasing the speed at which water flows. This has decreased the chances that water will spill over the banks. The larger substrate materials that made the creek bed stable — boulders, gravel, and logs — have been washed out, but are not being replaced. Instead, the creek bed is becoming ever finer and more prone to being further incised. In this environment, salmon eggs are more likely to be washed away.

Wander out the back door of the tasting room at Truett Hurst Winery in Sonoma County, California, and follow the dirt path to the red Adirondack chairs next to Dry Creek. Look just downstream to the side channel that splits off the main waterway. You will see sets of interwoven logs and overturned trees with roots that splay along the banks. These aren’t the result of a particularly rough storm — they are there by design. As Dry Creek rushes by, these logs and root beds point the way to a newly excavated side channel — prime habitat for spawning and juvenile salmon.

In freshwater waterways along the coast from Marin to Mendocino counties, agencies are restoring salmonid streams to create habitat diversity, areas that provide deep pooling, predator protection, and side channels of slower-moving water. California salmon are in dire straits. Decades of dam building and development have destroyed or altered salmon habitat, eliminating the diversity of habitat these fish need.

As a result, salmon populations have plummeted. The number of coho salmon that return to the California waterways from the Pacific Ocean each year has dropped from around 350,000 in the 1940s to less than 500 in 2009. Although they’ve rebounded slightly, numbers are still 90 percent to 99 percent below historic levels, and many scientists are worried that California’s historic five-year drought followed by an exceptionally rainy winter could wreak further havoc.

Salmon provide enormous environmental and economic benefits. They are an integral component of marine and freshwater foodwebs and play a role in transporting nutrients from the ocean into rivers. In California, salmon are the backbone of a $1.5 billion commercial and recreational fishing industry.

The Warm Springs Dam, which crosses Dry Creek, is one of two drinking water sources for around 600,000 customers in Sonoma County, but the year-round flows it produces are a problem for salmon.

“Dry Creek is a tremendous misnomer,” says David Manning, environmental resources manager at the Sonoma County Water Agency. “It flows so quickly that it doesn’t provide habitat for steelhead and coho,” and young fish are often washed downstream. To combat this, Manning and others are building “off-ramps” that will allow salmon to exit the Dry Creek freeway.

Read more at: Dams Be Damned: California Rebuilds the Salmon Habitat It Destroyed

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