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US Fish & Wildlife Service FieldNotes

ANTIOCH DUNES NWR: River Dredging Project Pays Unexpected Dividends for Endangered Species

Region 8, January 17, 2014
Dredged sand and water from the San Joaquin River is piped to the Antioch Dunes National Wildlife Refuge in Northern California
Dredged sand and water from the San Joaquin River is piped to the Antioch Dunes National Wildlife Refuge in Northern California - Photo Credit: n/a
The endangered Lange's metalmark butterfly's only natural habitat in the world is the Antioch Dunes National Wildlife Refuge.
The endangered Lange's metalmark butterfly's only natural habitat in the world is the Antioch Dunes National Wildlife Refuge. - Photo Credit: n/a

By Doug Cordell

The banks of the San Joaquin River, in the northeastern reaches of the San Francisco Bay estuary, were once lined with sand dunes twelve stories high. But decades of sand mining and encroaching development from heavy industries like shipbuilding have reduced the dunes to a few patches of land along the river, squeezing out much of the endemic wildlife that once called the dunes home. Two of those patches are the neighboring units of the Antioch Dunes National Wildlife Refuge—55 riverfront acres, tucked between a shipyard and a gypsum processing plant, that, at the time they were set aside in 1980, constituted the smallest national wildlife refuge in the country and the first ever created to protect endangered plants and insects.

Without a natural influx of sand, however—something that hasn’t happened since the adjacent dunes along the river were lost to development—even the protected enclave of the Antioch Dunes refuge struggles to maintain the riverine dune habitat that supports the federally endangered Lange’s metalmark butterfly, Contra Costa wallflower and Antioch Dunes evening primrose.

That’s why an innovative arrangement in October, 2013 among the refuge, the nearby Port of Stockton and the U.S. Army Corps of Engineers was such a notable achievement. With the agreement among the three parties, sand that was dredged from the San Joaquin River to clear navigation channels for cargo ships was pumped to the refuge for use in restoring dune habitat.

“This solved two big problems for us,” says Don Brubaker, the manager of the Antioch Dunes National Wildlife Refuge for the U.S. Fish and Wildlife Service. “One, it gave us a large enough supply of sand to begin to restore the high-dune habitat that the endangered species on the refuge historically thrived on. And, two, it didn’t cost us a penny.”

Brubaker gives special credit to the San Francisco Bay Conservation and Development Commission for alerting the Port of Stockton about the refuge’s need for sand. He points out that the Port saved money, as well, since the dredged sand didn’t have to be hauled farther away for disposal.

“Partnership and cooperation among agencies were the keys to making this thing happen,” he adds, “and everyone benefitted.”

The sand was dredged from the river bottom with a hydraulic suction, transported a short distance to the refuge and fed into a series of berms that separated out water. A total of 40,000 cubic yards of sand were brought in at no cost to the refuge. By comparison, in 2009 the refuge paid $25,000 to bring in only 1,500 cubic yards.

One challenge the refuge has faced in previous such efforts is keeping the sand free of the invasive weeds that, in recent years, have choked out not only the endangered plants on the refuge but the host plant for the endangered butterfly.

By bringing in such a large amount of sand in the most recent operation, the refuge will be able to build higher dunes, which drain better and allow for more naturally shifting terrain—two conditions for preventing the growth of invasive plants. A stacker will load the dried sand into a hopper so that it can be dropped to the ground from an elevated height, preferably on windy days, to blow out any detritus or other bio-matter that might feed invasives.

“We’re looking to mimic the habitat that we know has worked for the endangered species here in the past,” says Brubaker.

He notes that the Army Corps left the transport infrastructure in place so that more dredged sand can be brought to the refuge next year. He is also hopeful that other operators in the area looking to dispose of sand will be able to use it.

“This could really help the refuge.”

Doug Cordell is the Public Affairs Officer at the San Francisco Bay National Wildlife Refuge Complex in Fremont, California.

Contact Info: Doug Cordell, 510-774-4080, doug_cordell@fws.gov