Healthy creeks mean a safer Petaluma watershed

A restoration project along Adobe Creek will improve fish habitat, and is part of a larger effort to reduce flooding by enhancing the flow of water into the Petaluma River.|

The Sonoma County Water Agency is in the midst of a project to restore vegetation and improve flood control capacity along a southern stretch of Petaluma’s Adobe Creek, partnering with the United Anglers of Casa Grande High School in an effort to maintain a key habitat for steelhead trout in the process.

The approach represents the kind of ecosystem maintenance projects that now occur on an ongoing basis throughout Petaluma and countywide. Gone are the days of lifeless U-shaped drainage channels, replaced by an approach that views such waterways as ecological assets, according to leaders in the effort.

“It’s that balance of supporting habitat while providing flood control,” said David Royall, an engineer with the water agency.

Runoff from approximately five square miles of land in Petaluma flows to Adobe Creek, an eight-mile waterway that runs south from Sonoma Mountain to the Petaluma River. The current work is focused on the southernmost stretch, between Lakeville Highway and Shollenberger Park.

Petaluma began diverting all of the water from Adobe Creek in 1880, a practice that continued for more than a century. The United Anglers formed in 1984 to restore the creek, and ultimately succeeded in lobbying the city to stop diverting from the waterway in 1992.

The anglers group also operates a fish hatchery at the Casa Grande High School campus and regularly monitors the creek, which today is considered an important waterway for the migration and spawning of several salmon species.

“It is one of the most prominent creeks for steelhead,” said Dan Hubacker, director of the program and a former student participant in the United Anglers of Casa Grande.

Hubacker said his group’s relationship with the water agency had in the past been less harmonious. Creek projects in previous decades had occurred with less of a focus on surrounding habitat, he said, which had stymied the United Anglers’ efforts to support salmon migration.

Yet today, habitat restoration is considered a high priority as agencies embark on various work in waterways throughout the county. The Water Agency consulted the anglers group before setting out on the Adobe Creek project, determining whether seemingly inconsequential features of the creek served as spawning areas, for example.

“There’s definitely been a shift to put in these kinds of practices,” Hubacker said. “It’s finding a common ground.”

The Adobe Creek work is required to offset environmental impacts from the Caltrans project to widen Highway 101. Crews, including youth from the Conservation Corps of the North Bay, are currently removing non-native plants and other vegetation negatively impacting the waterway. Later work will include the removal of excess sediment, the planting of beneficial species and the creation of features to improve salmon migration.

The area is considered an important habitat for the threatened California red-legged frog species, salt marsh harvest mouse and potentially Sacramento splittail and green sturgeon, according to the Water Agency.

“The habitat in that area is extremely important,” said Royall, of the Water Agency.

Among the highest priorities in the project is the support of a robust tree canopy, which creates shade that limits the growth of other plants that might encroach on the waterway and impact both its flood control capacity and the passage of migratory fish. By creating the right mix of plant species, the long-term aim is to make such channels more self-sustaining and require less hands-on work to maintain.

“You wouldn’t know they were flood control channels. They don’t look that way,” said Michael Thompson, assistant general manager for the water agency, during a recent tour of flood control projects in Petaluma. “We essentially have 50 to 100 miles of linear parks we maintain each year.”

(Contact Eric Gneckow at eric.gneckow@arguscourier.com. On Twitter @Eric_Reports.)

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