[http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2012/01/01/BAPG1MFUB0.DTL]
An all-but-forgotten island in the northwest corner of Richardson Bay has become a testing ground for the notion that a functioning ecosystem can be built out of human excavation refuse.
The name Aramburu Island may conjure up exotic images, but the 17-acre atoll on the east side of Strawberry Point is really just a giant pile of dirt scraped off a hillside and dumped unceremoniously by a developer into the bay.
This decidedly unromantic mound of soil, named after a former Marin County supervisor, is now being transformed into the utopian vision of the Richardson Bay Audubon Center and Sanctuary, which is using $2.4 million to create a nature preserve and wildlife refuge surrounded by shoreline habitat.
"We are hoping to provide super-high-quality habitat for shorebirds, migrating birds and harbor seals, and we are also hoping it will stop erosion, which will improve water quality in the bay," said Brooke Langston, the executive director of the audubon center in Tiburon. "Once the island is restored, it will also provide protection from sea-level rise for homes along the bay."
New shoreline -
Workers removed invasive plants and trees from the island last summer and fall, and created an entirely new rocky shoreline around the island using thousands of cubic yards of sand, gravel and shell substrate barged in from dredge projects in San Francisco Bay.
The idea is to replace the silty, eroding mud that surrounds the island with natural soils that harbor the bugs, worms and crustaceans that shorebirds prefer and harbor seals favor for basking.
Workers removed nonnative weeds, ice plant and acacia, and the Audubon center is growing native seeds collected along the shores of Richardson Bay, an ecologically rich estuary surrounded by Sausalito, Mill Valley, Belvedere and Tiburon.
High school volunteers were out pulling weeds and picking up trash last week, but the bulk of the restoration work is expected to be finished next spring and summer. The plan, Langston said, is to plant the seeds during the first rains next year.
"We are changing the topography of the surface of the island and creating a living shoreline," she said. "As sea level rises, the beach will react to it by moving upland."
Accidental opportunity -
It is an unusual opportunity borne out of the general ignorance of environmental issues that existed in the late 1950s and early 1960s. That was when an artificial peninsula known as the Strawberry Spit was created out of material dredged from navigational channels. Upland soils excavated during development of the adjacent Strawberry Point were then piled on top, leaving an entirely unplanned and unnatural landscape.
In the late 1960s, the abandoned spit became a popular haul-out site for harbor seals, with as many as 30 percent of the San Francisco Bay population taking refuge there. The seals gradually stopped using the island, most likely as a result of human disturbances and the silting over of an adjacent deepwater channel. The last seal was seen on the island in 1985.
In 1987, a 165-foot channel was dug through the northern end of the spit, creating a 34-acre island, which was named after former Supervisor Al Aramburu, an early member of the San Francisco Bay Conservation and Development Commission.
The island, which is owned by Marin County and managed by the Marin County Department of Parks and Open Space, was supposed to become a wildlife preserve as mitigation for a nearby development, but it has been sitting there untouched for a quarter of a century. Half of the island eroded over the years, and the upland area became overgrown with nonnative plants and grasses.
A rediscovery -
Langston said she knew little about Aramburu until sick and dead birds began washing up there after the 2007 Cosco Busan oil spill, a subsequent sewage spill and then an outbreak of avian cholera.
"It was the first time we started paying attention to it," she said. "It was potentially good habitat ... so we went to Marin County and proposed a restoration."
The work is being bankrolled by the California Regional Water Quality Control Board, the Sewerage Agency of Southern Marin, the National Oceanic and Atmospheric Administration, the Marin Community Foundation and the National Fish and Wildlife Foundation. Money for the project is also expected from the Cosco Busan spill settlement.
Langston said she expects to see a major increase in the number of shorebirds and songbirds and is hoping the harbor seals return after a new deepwater channel is created on the southern end of the island for them.
"We don't get many opportunities to create new nature," said Langston, whose organization is required to monitor the island ecosystem for five years after the work is done, "so this is a really exciting, thrilling opportunity."
Environmental researchers Brooke Langston (left) and Lara Martin dock their boat at Aramburu Island.
Photo: Brant Ward / The Chronicle
Research technician Lara Martin (left) and Brooke Langston, executive director of the Richardson Bay Audubon Center and Sanctuary in Tiburon, gather litter on Aramburu Island, which is being transformed into a nature preserve and wildlife refuge. "We don't get many opportunities to create new nature," says Langston, whose group will monitor the island ecosystem.
Photo: Brant Ward / The Chronicle
An osprey flies from a pole on the island.
Photo: Brant Ward / The Chronicle
Audubon Center workers are gathering bay soils to be transferred to other areas of the island to promote foods for Pacific seabirds.
Photo: Brant Ward / The Chronicle
A sign naming the preserve and a large No Trespassing sign are the only signage on the island.
Photo: Brant Ward / The Chronicle
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