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Arroyo Seco Foundation

News of the Arroyo


Title:

Salinas River test project deemed success

Subtitle:

Date:

2014-11-06

Summary:

November 6, 2014 - The Arroyo Seco in Monterey County, our sister river, was also once a steelhead river. Now new efforts are being made to improve habitat and conditions on the connecting links to the Arroyo Seco. -

Author:

Dennis L. Taylor

Publication:

The Californian

Content:


John Rohrbough from the California Environmental Protection Agency photographs the river bed next to a stand of arundo donax, the tall perennial cane, as part of the Salinas River Multi-benefit Demonstration Project on Wednesday in Gonzales. (Photo: Jay Dunn/The Salinas Californian )

The first collaborative effort to clear the Salinas River of brush and debris to control flooding, while at the same time protecting native species habitat, was unveiled Wednesday along a stretch of river just outside of Gonzales.

The practice of bulldozing the stream bed, which was halted in 2008 by state and federal regulators because universal clearing of sections of the river threatened endangered species, particularly steelhead, was intended to increase channel water velocity by removing impediments to flow. When the river is clogged with vegetation, a damming effect can cause the river to spill its banks onto valuable cropland.

Growers lined up on one side of the river; environmentalists and regulators on the other side, dug their heels into the silt and stared menacingly at each other for eight years. Then in September 2013, representatives of The Nature Conservancy sat down shoulder-to-shoulder with farmers to begin planning ways in which everyone would walk away from the table secure in knowing they got something out of it.

The Nature Conservancy, or TNC, has earned respect over the years by working collaboratively with growers and ranchers by purchasing agricultural easements to prevent developers from buying up prime farm- and rangeland and turning the Salinas Valley into five-acre parcels covered with McMansions.

So in October of that year, TNC began holding workshops with growers and stakeholders to understand everyone’s needs and begin a tedious process of drafting plans for demonstration projects – one near Chualar and one near Gonzales. Combined, the projects span 11.5 miles of the river.

The resulting design mimics the natural braided channels of the river. During winter rains, the river rarely stays within a single channel, rather spreads out into disjointed channels that can resemble braids. Hydrologists and other scientists studied velocity, depth and direction of these braids to determine how best to use these secondary channels.

“When the floodwaters came, we watched where the river wanted to go,” said Jennifer Biringer, the senior director of TNC. “Instead of fighting it, we learned to go with it and allow the channels to braid in and out of each other.”

One conclusion of the research is the limitations of channel maintenance in general. Even if all the debris were removed from the channels, the river would still be prone to even five-year floods – flooding that occurs on average once every five years.

The computer modeling also shed light on the problems created by the old practice of bulldozing randomly. It might work well to prevent some flooding along that farmer’s section of the river, but it only makes flooding worse for the farmer’s downstream neighbor, Biringer said.

Creating multiple pathways for the water to flow eases flooding and helps migrating steelhead by creating low-flow areas, she added. Steelhead do not spawn in the Salinas River, but use the river to swim upstream to their historical spawning grounds on tributaries such as the Arroyo Seco River.

It’s a long haul from the ocean to the Arroyo Seco, and the steelhead need to rest in shaded water along the way. Consequently, the project design focused on removing tons of the invasive cane-like weed arundo, which sucks up water and provides very little wildlife habitat. So biologists would tag trees with ribbon, and when the mowing commenced, the small, maneuverable mowers would take out the arundo but steer clear of the valuable trees and other native vegetation.

“In fact, no native vegetation was touched,” Biringer said. “I’m confident that it is a successful step in the right direction. Growers are very pleased.”

Dennis L. Taylor covers environment and water issues for TheCalifornian.com. Follow him on Twitter @taylor_salnews.

Who was involved

Local partners in the Salinas River flood control effort included the Monterey County Water Resources Agency, the Salinas River Channel Coalition, Grower Shipper Association, and Monterey County Resource Conservation District. Federal, state and regional government agencies included Army Corps of Engineers, National Oceanic & Atmospheric Administration, U.S. Fish & Wildlife, California Central Coast Water Board, California Department of Fish & Wildlife, and Environmental Protection Agency.

The project has also received strong support from U.S. Rep. Sam Farr, Assemblyman Luis Alejo, state Sen. Anthony Cannella and Monterey County Supervisor Simon Salinas.

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Arroyo Seco Foundation, 570 W. Avenue 26 #450, Los Angeles, CA 90065-1011
PO Box 91622, Pasadena, CA 91109-1622 (323) 405-7326 info@arroyoseco.org