Bay Crossings Article

Protecting the Bay’s Most Sensitive Areas

Deb Self, Executive Director
From the January 2010 edition of Bay Crossings

When I received news of the Dubai Star oil spill in late October, I immediately turned to the Bay’s oil spill contingency plan, the document that governs how federal and state government agencies respond to an oil spill. The plan contains important information about the Bay’s sensitive sites, such as the seasonal locations of rare and endangered species, and specific strategies to prevent oil from impacting more than 200 particularly sensitive Bay and coastal shorelines. As the oil spread in the hours following the Dubai Star spill, I grew worried about the shorelines in the path of spreading oil.

Here at Baykeeper, we’re particularly concerned about impacts to the Bay’s 232 state-designated sensitive sites—mud flats and marshes, rocky cliffs, lagoons and sloughs. These mini-ecosystems have unique biological and chemical conditions that are vital to sustain rare plants and animals. For example, the beautiful salt marsh yellowthroat bird and tiny endangered salt marsh harvest mouse only live in the salt marshes around the San Francisco Bay. Sensitive sites ring the Bay, from Paradise Cove on the Tiburon Peninsula to Bair Island in the South Bay to Suisun Marsh in the northern reaches of the Bay. These sites are especially important to the healthy functioning of San Francisco Bay, and they are also the most vulnerable to harm by oil spills.

One of the key lessons learned from the 2007 Cosco Busan spill is that oil causes the greatest injury once it has spread from the site of the spill and washed into shoreline ecosystems, especially marshes, which are impossible to clean. It is vital, therefore, that top priority marshes, mudflats and other sensitive sites are shielded with protective booming—our best shot at keeping oil from touching the shorelines.

Some bird species and marine mammals that depend on rocky outcroppings and swift water tidal areas have particularly tough luck when it comes to oil spills, because these areas are difficult to effectively boom. It’s just not feasible to keep oil off of the rocky bluffs of Angel Island and the Marin Headlands, or out of the entrances to Bolinas Lagoon and Drakes Estero.

Oil spills have also taken a toll on the Bay’s eelgrass beds, which provide key habitat for marine life in San Francisco Bay. Eelgrass beds are essential to ongoing efforts to restore the native Olympia oyster and also provide a critical spawning site for Pacific herring, the Bay’s struggling commercial fishery. Unfortunately, over the past few decades the size and number of eelgrass beds in San Francisco Bay has been steadily declining. What used to be vast meadows of eelgrass have been reduced to a few key beds near Richardson Bay, Point Richmond and Alameda. The remaining eelgrass beds and the marine life they support are vulnerable to oil spills. For even though the Dubai Star spill was relatively small—spilling approximately 400 gallons of fuel compared with Cosco Busan’s 53,000 gallons—it resulted in six miles of oiled Alameda Island coastline, jeopardizing thirty acres of fragile eelgrass beds.

There also is growing evidence that the Cosco Busan spill may have reduced numbers of Pacific herring, a Bay fish that lays its eggs in eelgrass beds, seaweed, and pier pilings that were contaminated by bunker fuel during the 2007 spill. A damage assessment following the spill revealed that herring eggs near the oil spill were deformed, stunted, and twisted, all signs of exposure to the toxic components of petroleum. The Pacific herring fishery was closed by wildlife managers this September due to low numbers, leading some scientists to conclude that the population has not been able to rebound from the impacts of the Cosco Busan spill.

In the coming months Baykeeper will be investigating the Dubai Star response and helping to document the spill’s impact on sensitive sites. For more information about Baykeeper’s work to protect the Bay from oil spills, visit us at