Water, wildlife returning to Pacheco Marsh and Walnut Creek | News
Since the break of the Suisun Bay levees nearly six months ago, the landscape of Pacheco Marsh has changed dramatically.
It’s closer to being a waterscape now, with the 5.32 miles of canals dug by earth-moving machinery last year now full of water from the bay, flowing upstream or downstream, depending on the tide. . Ribbons of yellow wildflowers – dotted with orange poppies – meander through the marsh.
Waterfowl are starting to appear – rabbits and coyotes were there before, although they’re easier to find now that the wildlife sanctuary is taking on a more functional form (coyotes have been spotted right next to (of course) the chief coyote plant project Paul Detjens pointed this out a few minutes earlier).
There are also around 31,000 milk cartons dotting the landscape, as well as miles of irrigation pipes that will stand for three years.
Milk cartons protect native plants that have been planted in the ground. The type of plant depends on the area and “how much salt water they like,” Detjens said. Much of it will be habitat for the endangered salt marsh mouse.
“They’re 100 percent indigenous,” said Detjens, senior civil engineer for the Contra Costa County Flood Control District. “There will be a mixture of wildflowers and grass in the transition areas. We are not planting the tidal channel. This will be taken care of by seeds that will come up with the tide.”
“Now that we’ve introduced the tides it’s really starting to flourish and I’m happy to see that,” Detjens said.
The goal of the Lower Walnut Creek Restoration Project is to restore 300 acres to their natural state, before the intervention of 19th century industry.
Just over the hill from the Al McNabney Swamp — across Interstate 680 from the Martinez Refinery Co. — it’s the largest public works project in the county’s history.
The Walnut Creek watershed is the largest in Contra Costa, draining more than 150 square miles from eight towns into a swamp that over the past century has become a dumping ground for dredging and an industrial buffer for the bay.
Engineers want to improve the region’s flood-carrying capacity, while naturalists want conditions closer to those that existed before humans channeled the swamp and brought industry there.
The marsh and Walnut Creek, at the eastern edge of the marsh, supported grizzly bears, elk, salmon, and steelhead trout until the mid-1800s (opinions vary as to whether restoration will bring the fish back spawning). Although Detjens said, “The fish start to come up and get big and happy before they go.”
The wetlands filled in over the years, and merchant ships sailed up Walnut Creek. Over the decades refineries were built and much of the region was forgotten.
The county purchased 122 acres of swamp in 2003 from a towing company that previously planned a scrap there. The nearby Marathon Oil refinery purchased 18 adjacent acres formerly used for sand mining and donated them to the land trust in 2020.
Detjens said the project was meticulously and scientifically planned, down to the exact location of each plant.
“It’s something different from ‘We build a meadow and wait for the rain to keep the plants alive,'” Detjens said. “It’s really an estuary in that it takes water from the bay into an interface with groundwater. It’s a bit more complex nuance of how it’s revegetated.”
It was also planned with the future in mind.
“This is actually the area we designed for sea level rise adaptation,” Detjens said, standing on what will become a pathway. “Instead of having a steep slope, we have this gradual slope, so that as sea levels rise in the coming decades, this habitat may actually slowly migrate upwards and plant communities may evolve and change as conditions change. That’s one of the reasons you don’t see a traditional levee with a real steep slope here.”
The John Muir Land Trust will manage the site, which they believe will become a birding destination. Even before the project began, more than 80 species of birds were found in the Pacheco Marsh, including short-eared owl, white-tailed kite, American kestrel, northern harrier, and shrike. migrant.
The land trust will get to work later this year, developing 2.6 miles of trails on 140 acres, with multiple elevated viewpoints for birdwatching and other educational resources. The marsh will also include three kayak ramps, a staging area and a parking lot at the south end of the marsh.
“Once constructed and open to the public, these public access features will provide environmental education and wildlife-compatible recreation to local and regional visitors for generations to come,” said John Muir Land Trust Executive Director Linus Eukel, in an email.
Detjens pulled non-native plants from the ground as he spoke. He said the project is one of the highlights of his 30-year career.
“This whole area, life is coming back to it,” Detjens said. “We are very happy to see that the plan is coming to fruition and that it is actually working.”