Restoring Antioch Dunes National Wildlife Refuge

December 2, 2013

eaning on the hood of his pickup truck, parked just inside a chain link fence Louis Terrazas rustles through a thick folder of documents that describe the parcel of open space he is trying to restore. The hum of machinery echoes from a yellow bulldozer moving about the industrial lot next door and under the glaring sun Terrazas turns through the plastic pockets, narrating each document inside. There’s a graph of butterfly health, a series of orange bar lines that diminish as they run off the page. There’s a technicolor, bathymetry map that plots the bumps and canyons of the nearby river. And then a black and white crosshatched plan of the area that divides it in two labeling one ‘Stam’ and the other ‘Sardis’ in square speech bubbles. In isolation, each of these documents is a standard part of conservation, outlining projects and presenting photographs that remind us of what we are trying to conserve. But as a whole, they tell the story of the rise, fall and possible rise once more of Antioch Dunes National Wildlife Refuge.

Nestled between a gypsum processing plant and the Fulton Shipyard—where workers built military vessels during World War II— the refuge could be said to reside  between a rock and a hard place. It is the last remaining piece of a riverine sand dune ecosystem that once blanketed present-day Antioch with dunes towering at over 120 feet and stretching some 800 feet inland from the banks of the San Joaquin River. What remains of it today is a 55-acre plot of land that was set aside in 1980 by the U.S. Fish and Wildlife Service (USFWS) to save three endangered and endemic species—two plants and one butterfly—that had thrived in this habitat of shifting sands.

Contra Costa Wallflower in bloom. Photo: Rachel Hurt.
Contra Costa Wallflower in bloom. Photo: Rachel Hurt.

At the time of its creation, it was the smallest national wildlife refuge in the nation, and the very first dedicated to the preservation of plants and insects. Now it is the smallest and easternmost unit of the San Francisco National Wildlife Refuge Complex, and it’s now the site of an ambitious experiment in ecosystem restoration. The diminutive characters at the center of this ecological drama are the Antioch Dunes evening primrose, a short-lived perennial plant with large white flowers; the Contra Costa wallflower, a yellow flowered herb in the mustard family; and the Lange’s metalmark butterfly. About the size of a quarter, this burnt orange, black and white butterfly is closely tied to its host plant—the naked stem buckwheat, a native plant that also grows in the refuge.

In the past, several smaller restorations were undertaken by FWS staff thanks to sand donations from companies such as PG&E. In 1991, about 7,000 cubic yards of sand were contoured to mimic the historic, open sand dune environment and replanted with endemic and native species. For a time the native flora and fauna flourished: Following restorations in the early and mid ‘90s, there was a spike in the population of Lange’s metalmark butterfly, which numbered at 1,079 in 1999. However the good times didn’t last as the nonnative overwhelmed the replanted vegetation. Just 28 butterflies were counted in this year’s peak count in the Sardis Unit—the 14-acre eastern section of the refuge. Even worse in the larger Stamm unit, there have been no butterflies counted for the past two years. The butterfly’s absence at Stamm, and low numbers at Sardis prompted the U.S. Fish and Wildlife Service to undertake more dramatic and concerted action to keep the butterfly from extinction. At the same time, the absence of the butterfly at the Stamm unit has given the FWS a window of opportunity to take a more all-out approach to habitat restoration than would have been possible if the butterfly were still present.

Yelling over the rattle and whistle of a passing freight train, Terrazas explains that the natural sand dune system is “broken,” its formerly shifting sands locked in place by a mat of invasive plants including winter vetch, a legume that smothers the endemic wallflower and evening primrose. “With the invasive grasses and without an influx of natural sand, the dunes have been stabilized,” he said. “So we have to try and provide them with disturbance.” The defining feature of a sand dune system is of course, the sand, and since early last year Terrazas—a wildlife refuge specialist with the U.S. Fish and Wildlife Service—has been in the market for some…and large quantities of it. By introducing vast amounts of sand, the FWS will be able to cover over and smother the invasive mats, and then, hopefully, reconstruct an environment able to support healthy populations of native species.

A Lange's metalmark butterfly feeding. Photo: Louis Terrazas.
A Lange’s metalmark butterfly feeding. Photo: Louis Terrazas.

errazas’ search for sand struck gold when the California Department of Fish and Wildlife partnered with the Port of Stockton and the U.S. Army Corps of Engineers to move dredged sand from the San Joaquin River to the Stamm unit. Each year the river has to be dredged to clear the channel for large ships bringing cargo to the Port of Stockton. In the past, the spoils were offloaded on nearby Sherman Island or used for levee restoration projects. This partnership means that for the next ten years or so, dredged sand will pumped on to the refuge. “It’s been my goal to find projects that will benefit from reusing the dredged material,” said Jeff Wingfield, the Port’s director of environmental and government affairs. “We were thrilled to have the opportunity to place the material at the refuge for the restoration project.”

As he walks towards the river, Terrazas explains that prior to the dredging, the unit was divided into four sections of roughly 10-acres each to allow FWS staff to comprehensively restore each area. Over the course of ten days, workers from the Corps of Engineers moved approximately 40,000 cubic yards of sand from the bottom of the river to the refuge using a hydraulic cutter-suction dredger. The sandy slurry was pumped through a series of large pipes, bringing it out of the river and separating most of the sand from the water before spewing any excess water back into the river through an outfall pipe.

Bulldozer tracks and piles of sand cover the Stamm unit at Antioch Dunes National Wildlife Refuge. Photo: A Bergamin.
Bulldozer tracks and piles of sand cover the Stamm unit at Antioch Dunes National Wildlife Refuge. Photo: A Bergamin.

Now, a month after the first stage of the dredging has been completed, the Stamm unit resembles a large sandbox with bulldozer tracks crisscrossing the area like footprints on a beach.  “We’ll probably start getting a lot of those guys,” Terrazas says, gesturing to the killdeers— medium-sized birds that gravitate to open sandy habitat— perched amid a tire ridge. Over the coming months the FWS is planning to dump sand on a smaller adjacent two-acre area, to smother the remaining invasive plants and keep them from recolonizing the target area. Terrazas says that FWS staff will then begin planting this small area with native species, including the two endangered plants. Later in 2014 more sand will be offloaded in the first 10-acre section to further build the dunes before they are manipulated and a more extensive replanting takes place. The results from that effort will then guide work on the remaining 10-acre sections. Will all of this work allow the remnant sand dune system to finally move away from its past as a series of sand bumps and nonnative plants and become an ecosystem able to support its endemic species? “It’s a total learning process for us,” Terrazas says. “We’re basically figuring things out as we go.”

But the basics are largely there. Terrazas suggests that they will start building in the west to prevent the sand from being blown off the property by the prevailing eastward winds. FWS staff may also take into account the endemic species’ preferences: While the Antioch evening primrose prefers open areas, the Contra Costa wallflower grows best on shady north facing slopes and although Lange’s metalmark butterfly is the most finicky of the species, a plentiful supply of its host plant may shepherd the population back to the area. The return of the butterfly to this newly restored habitat will also get a boost from a captive rearing program undertaken by FWS and the Southern California-based Urban Wildlands Group back in 2007. “The butterfly propagation project is kind of like our insurance policy,” Terrazas said. “It goes hand in hand with the sand dune restoration as we want to keep the butterflies around and then also have a site to release them in the future.”

Antioch Dunes evening primrose in bloom. Photo: Antioch Dunes National Wildlife Refuge.
Antioch Dunes evening primrose in bloom. Photo: Antioch Dunes National Wildlife Refuge.

Back at the chain link fence at the edge of the refuge Terrazas packs his truck, ready to move to the Sardis unit. From the other side of that same fence, looking in, it can be hard to imagine the refuge thriving once again. But between this rock and this hard place, there is Terrazas—a dedicated FWS biologist; there are the refuge’s three endemic species clinging to what is left of their home; and there is the possibility that not only a landscape, but an ecosystem, can be rebuilt, with every grain of sand.

Alessandra Bergamin is the Bay Nature Online Editor.

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