Final dyke lifting at the Pacheco Marsh restoration – NBC Bay area

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Before crossing the last dike preventing seawater from rushing into Pacheco Marsh for the first time in generations, workers rushed this week to make sure the water wasn’t flowing the wrong way.

Record-breaking storms last weekend brought more than 7 inches of rain to the swamp southeast of the Benicia-Martinez Bridge, forcing workers to pump over a million gallons of rainwater this week to get the desired effect in Friday’s flooding ceremony.

“The storm we had on Sunday was not there,” said Paul Detjens, project manager and senior civil engineer for the Contra Costa County Flood Control District. “Locally, it created problems for us here. A week ago, this canal was dry. And now it’s filled with rainwater, and in an hour it’ll be full of tidal water.

“Bring it. We are ready,” he said.

An hour later, as the movers dug the last dirt barrier, to scattered applause among the guests, event host and TV personality Doug McConnell announced, “The water is in. And it is coming in. at home.”

Friday culminated nearly 20 years of work to restore 200 of the project’s 300 acres to their natural habitat, before 19th-century industry altered its landscape.

Contra Costa County spent $ 11 million on the Lower Walnut Creek Restoration Project, the largest public works project in the county’s history. The site is located just above Al McNabney Marsh Hill, across Interstate 680 from the Martinez Refining Co.

After the county supervisory board approved the $ 11.285 million contract with Four M Contracting Inc. in March, the excavators were in the mud a few weeks later. Now that the tidal water is backing up into the swamp, the John Muir Land Trust can finish transforming the area into a bird watcher’s paradise and a recreation destination.

“From there, the groundwork for public access was laid,” said Linus Eukel, executive director of John Muir Land Trust. “We are essentially doing this with public access. Our hope is that we will get there by 2023.”

The earthworks are not done. Three elevated panoramas over 20 feet high will be created, surrounded by new hiking trails, boardwalks, interpretive panels and bridges on the northern part of the marsh. A massive transport of native plants will be reintroduced, a rich habitat for the endangered salt marsh harvest mouse.

The Mt. Diablo Audobon Society has already recorded over 80 species of birds at Pacheco Marsh, species such as the short-eared owl, white-tailed kite, American kestrel, northern harrier and shrike. migratory.

“This habitat will just be inundated with new species of birds, and we expect it to be an international destination, but also an important local destination for children and families,” Eukel said, adding that the group had collected $ 3.5. million of its goal of $ 5 million. “We are in very good shape,” he said.

The Walnut Creek watershed is the largest in Contra Costa, draining more than 150 square miles of 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-resisting capacity, while naturalists want conditions closer to those that existed before humans channeled the swamp and introduced industry.

The Walnut Marsh and Creek were home to grizzly bears, elk, salmon, and rainbow trout until the mid-1800s (opinions vary as to whether the restoration will bring back spawning fish).

Then the humans arrived, filling in the wetlands and building dikes. Merchant ships moved up Walnut Creek, and other streams feeding Walnut Creek were diverted to humans developing Contra Costa. Refineries were built and the area was used as a dumping ground for dredging projects throughout the Bay Area.

The county bought 122 acres of swamp in 2003 from a towing company that had previously planned a dump there. The neighboring Marathon Oil refinery purchased another 18 adjacent acres formerly used for sand mining and donated them to the land trust in 2020.

Planners envision the Iron Horse Regional Trail, which now ends near National Highway 4, to extend an additional 3 miles along Walnut Creek to the Regional Waterfowl Reserve near Martinez. There will be another 2.4 miles of trails in the swamp, with a staging area, parking lot, birding blinds, and interpretive signs in the elevated areas.

The project will not only reduce stress on nearby shores as the sea rises in the years to come, it was also designed with the sea rising in mind. As the swamp transforms, the rising water mixes with more sediment, acting as a carbon filter helping to trap greenhouse gases.

Workers will add 31,000 new plants native to the area. It also covers other equipment, such as a kayak launch, which is still in the air. Although the entire project is called the Lower Walnut Creek Restoration, the northern section – the north section of Waterfront Road – will be managed by the Land Trust and called Pacheco Marsh. The southern section will include dike improvements.

Detjens called Friday “a real highlight of my career”.

“I’ve been with this from the start,” Detjens said. “I’m really happy to see the turnout. Typically a dike breach like this maybe 20 people show up, some people in orange vests and some people who donated money. we have about 250 people, I’m blown away by that.

“Whether you call it Lower Walnut Creek or Pacheco Marsh – it’s really the same thing – and it’s a really cool place.”


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