NOAA's Response and Restoration Blog

An inside look at the science of cleaning up and fixing the mess of marine pollution


How Would Chemical Dispersants Work on an Arctic Oil Spill?

This is a post by John Whitney, OR&R’s Scientific Support Coordinator for Alaska.

An Arctic Cod rests in an ice-covered space.

An arctic cod, a key part of the Arctic food web, rests in an ice-covered space in Alaska’s Beaufort Sea, North of Point Barrow. This species was one of the subjects of the research program on dispersant effects in the Arctic. (Shawn Harper/Hidden Ocean 2005 Expedition: NOAA Office of Ocean Exploration)

If there were a huge oil spill in the Arctic, would chemical dispersants work under the frigid conditions there?

And once dispersants break down oil into smaller droplets, how toxic are the oil and chemicals to key species in the short Arctic food web?

Would the dispersed oil and dispersant actually biodegrade in cold Arctic waters?

With Shell currently on track to drill several exploratory wells in the Chukchi and Beaufort Sea this summer, these are very timely questions—and finally, we are beginning to find some answers.

For the last three years, a special oil industry research group (called a “joint industry program”) has been trying to resolve these questions before any major oil exploration, development, and production happens off the northern Alaskan Arctic coastline. Lead scientists Dr. Jack Word of Newfields Environmental (Port Gamble, Wash.) and Dr. Robert Perkins of University of Alaska, Fairbanks, coordinated this research program to determine the viability of using dispersants on Arctic Ocean oil spills.

Oil impacts on Arctic food webs

The illustration, not associated with this study, shows potential oil spill impacts to wildlife and habitats in the Arctic Ocean. Click for larger view. Credit: NOAA/Kate Sweeney, Illustration.

Aiming for as realistic Arctic conditions as possible, they captured arctic zooplankton (krill and Calanus copepods, which are tiny marine crustaceans) as well as larval and juvenile fish (arctic cod and sculpin) from the coastal waters of the Beaufort Sea.

These organisms are key players in the Arctic food web and culturing them in order to conduct toxicity tests hopefully would reveal how negative impacts from oil and dispersants could cascade through the ecosystem. The researchers also conducted toxicity and biodegradation tests in actual waters collected from the Beaufort Sea.

Five oil companies were pooling their talents and financial resources to conduct these tests and gather information: Shell, ConocoPhillips, Statoil, ExxonMobil, and BP. As NOAA’s Scientific Support Coordinator for Alaska, I was fortunate enough to serve on a unique, yet very important, part of the group: the Technical Advisory Committee, which is composed of non-industry technical and non-technical stakeholders. We met once a month to discuss the results and advise them on ongoing scientific tests.

Drs. Word and Perkins and their colleagues recently presented the results of this research at a workshop in Anchorage, Alaska. The workshop began with Tim Nedwed of ExxonMobil making a strong case for immediate and robust access to all the major oil spill response options—mechanical methods, in situ burning, and dispersants—in order to deal with a large oil release in the Arctic or any other location.

Mechanical methods (e.g., skimmers) and in situ burning typically encounter spilled oil at low rates, historically removing only 5% to 15% of the oil on the water’s surface. This makes chemical dispersants a very attractive option when approaching a big spill using a large aircraft (such as a C-130) to deliver dispersants. After all, Dr. Nedwed pointed out, the ultimate goal of dispersants is to deliver a significant boost to the rate of oil biodegradation that happens naturally after most oil spills.

Here are some of the major findings from their research:

  1. Arctic marine species show equal or less sensitivity to petroleum after exposure than temperate (warmer water) species.
  2. The Arctic test organisms did not show significant signs of toxicity when exposed to recommended application rates of the dispersant Corexit 9500 by itself, which also tends to biodegrade on the order of several weeks to a few months.
  3. Petroleum does biodegrade with the help of indigenous microbes in the Arctic’s open waters under both summer and winter conditions.
  4. Chemical dispersants more fully degraded certain components of oil than petroleum that was physically dispersed (for example, from wind or waves breaking up an oil slick).
  5. Under various scenarios for large and small oil spills treated with Corexit 9500, the effects on populations of arctic cod, a keystone species in the Arctic, appeared to be minor to insignificant.

This workshop garnered attention from the oil industry, government regulatory and natural resource agencies, academia, Alaska North Slope residents, private consultants, and non-governmental organizations. It concluded with a brief discussion of Net Environmental Benefit Analysis, a scientific process of weighing the costs against the benefits to the environment, with emphasis on the importance of making this process both science-based and, at the same time, compatible with listening to the subsistence Alaska Native population, a significant and valuable voice in the Arctic.

John WhitneyJohn Whitney has served as the Alaskan Scientific Support Coordinator for NOAA’s Office of Response and Restoration for over 25 years. His responsibilities include primary scientific support to the U. S. Coast Guard, as well as to industry, government agencies, and stakeholders for oil spills and other hazardous materials response in Alaska’s offshore waters. John’s background is in physics and geophysics, earning a PhD in geophysics from the University of Washington in Seattle. Currently, John participates in deliberations with the Arctic Council Emergency Preparedness, Prevention, and Response working group and also chairs the dispersant working group of the Alaska Regional Response Team.

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Mapping How Sensitive the Coasts Are to Oil Spills

This is a post by the Office of Response and Restoration’s Donna Roberts, Jill Petersen, and Ashley Braun.

Pelican escaping oiled waters after the tank ship Eagle Otome spill near Port Arthur, Texas.

Pelican escaping oiled waters after the tank ship Eagle Otome spill near Port Arthur, Texas, in January of 2010. (NOAA)

The U.S. shoreline stretches 95,471 miles, from the coast of Alaska to the Great Lakes to the Gulf of Mexico. However, these shores vary greatly in type, in how people use them, and in which species of birds, fish, and wildlife inhabit them.

These differences affect how sensitive the shorelines are to spilled oil and other environmental hazards. NOAA works with the federal and state governments to produce Environmental Sensitivity Index (ESI) maps, which identify coastal locations that may be especially vulnerable to an oil spill.

This series of maps shows the shorelines, wildlife, and habitat most sensitive to oil, as well as the resources people use there, such as a fishery or recreational beach.

Environmental Sensitivity Index map close-up.

Shorelines on Environmental Sensitivity Index maps are color-coded by sensitivity to oil. Symbols mark localized areas for biological and human-use resources.

For example, an ESI map in North Carolina might indicate an estuary where piping plovers, a threatened shorebird, nest between March and August. It would also display a color-coded ranking revealing that the saltwater marsh is highly sensitive to oiling and show the presence of and contact information for a nearby marina.

Quick Decisions

When a shoreline is threatened by an approaching oil spill, responders must decide quickly which locations along a shoreline to protect. Making these decisions sometimes requires difficult tradeoffs. Having this valuable information ready beforehand helps spill planners and responders prioritize areas to protect from oil and identify appropriate cleanup strategies.

For NOAA’s Office of Response and Restoration, one of our main goals in oil spill response is to reduce the environmental consequences of both spills and cleanup efforts. We help create and maintain ESI maps to facilitate the decision-making process surrounding these efforts. Some of the human-use resources on ESI maps include potential access points and staging areas, including boat launches and airports, which would be useful during an oil spill response.

Digital Maps

We offer ESI maps—and the data represented on them—for all of the U.S. coastal states and territories. Besides traditional print maps, we also make the data available through geographic information system (GIS) technology, which allows a much greater level of detail. You can see what digital file formats are available and download maps for your geographic region.

While all of the digital ESI maps are available in a free format, our team also has developed a collection of tools to simplify viewing and querying the data in an advanced GIS format. One of our newer tools, the Seasonal Summary Tool, creates a personalized ESI map, giving a snapshot of everything going on in a specific region for a particular time of the year. This may be beneficial for responders looking at an area impacted by an oil spill.

Another feature of the digital maps and data is that they group together species with common habitats, behaviors, and feeding patterns. One ESI tool can take advantage of this grouping to allow users to view areas where only those groups, such as birds of prey, occur. The user can filter this information further to show only the areas where these birds may be nesting in June or show only federally threatened or endangered species.

Mississippi Dog's Paw Environmental Sensitivity Index Map

Mississippi Dog’s Paw Environmental Sensitivity Index Map, showing a GIS tool feature which allows the user to delineate noncontiguous boundaries on the map.

A variety of people make use of Environmental Sensitivity Index maps, from the U.S. Coast Guard and Bureau of Ocean Energy Management (BOEM), to the Army Corps of Engineers and state contingency planners and emergency responders.

ESI maps are a constantly evolving product for constantly changing coasts and are rich with complex information. Since 1990, Jill Petersen has been observing this evolution firsthand, through her work on Environmental Sensitivity Index maps for the Office of Response and Restoration.

While demonstrating some of the advanced GIS tools in 2011, Petersen highlighted one which also allows users to draw their own geographic boundaries. The boundaries she, a canine enthusiast, chose for the Mississippi map? A dog’s paw, of course.

Donna Roberts

Donna Roberts is a writer for the Emergency Response Division of NOAA’s Office of Response and Restoration (OR&R). Her work supports the OR&R website and the Environmental Sensitivity Index (ESI) mapping program.

Jill PetersenJill Petersen began working with the NOAA spill response group in 1988. Originally a programmer and on-scene responder, in 1991 her focus switched to mapping support, a major component of which is the ESI program. Throughout the years, Jill has worked to broaden the ESI audience by providing ESIs in a variety of formats and developing appropriate mapping tools. Jill has been the ESI program manager since 2001.

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Help NOAA Study Chemical Dispersants and Oil Spills

A plane releases chemical dispersant to break up an oil slick.

A plane releases chemical dispersant to break up an oil slick on the water surface below. Photo courtesy of the National Commission on the Deepwater Horizon Oil Spill and Offshore Drilling.

Help NOAA expand what we know about the effects of chemical dispersants on both spilled oil and the marine environment: funding for research projects is now available [leaves this blog].

The explosion and subsequent well blowout on the Deepwater Horizon drilling rig on April 20, 2010, led to the largest oil spill in United States history.

The unprecedented use of chemical dispersants on and below the ocean’s surface during this oil spill raised scientific, public, and political questions about both their effectiveness and their potential consequences for ecosystems and marine life in the Gulf of Mexico.

To help answer those questions, NOAA is partnering with the Coastal Response Research Center at the University of New Hampshire to fund research on dispersants and dispersed oil. The focus will be in the following areas: 1) dispersants and risk communication; 2) degradation of dispersants and dispersed oil; and 3) biological effects of dispersants and dispersed oil on surface and deep ocean species.

The request for research proposals is available at the Center’s website [leaves this blog]. Researchers interested in submitting a proposal need to turn in a letter of interest by May 15, 2012.

The Coastal Response Research Center was established in 2004 as a hub for oil spill research, development, and technical knowledge transfer. The Center is a partnership between the University of New Hampshire and the National Oceanic and Atmospheric Administration’s (NOAA) Office of Response and Restoration. The Center collaborates with other federal, state, and local research and development programs to promote effective protection, assessment, and restoration of coastal areas and resources.

The overall goal of the Center is to reduce both the potential for, and the consequences of, spills and other hazards threatening coastal environments and communities. Advances in science and technology relating to spills will be applied to other types of threats to coastal environments and communities, when possible.

Preventing a spill is always the preferred scenario, but as long as we explore, drill, and transport oil, there will be a chance for spills. And once oil is spilled, we can no longer prevent harm from happening to the marine environment, but we can reduce that harm through a combination of response measures. With our partner at the Coastal Response Research Center, we hope to improve the science of spill response before the next oil spill happens, so that when it unfortunately does occur, we are better prepared to deal with it.

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More Than Two Decades Later, Have Killer Whales Recovered from the Exxon Valdez Oil Spill?

With input from NOAA’s Alan Mearns, Gary Shigenaka, and Marilyn Dahlheim.

Orca breaching.

Killer whale breaching (NOAA Marine Operations Center).

Does a killer whale instinctively know how to avoid oil spilled on the surface of its watery home? At the time of the Exxon Valdez oil spill twenty-three years ago, scientists and oil spill experts presumed that the answer was “yes.”

They thought marine mammals were “smart” enough to steer clear of spilled oil, which possibly could harm their skin and eyes or irritate their lungs with hazardous vapors.

Yet, within 24 hours of the tanker Exxon Valdez grounding on Bligh Reef, killer whales were photographed swimming through iridescent slicks of oil in Prince William Sound, Alaska. No one was quite sure then how this exposure to oil might affect the health of killer whales living there. For most oil spills, we don’t know how well individual species were faring before oil invaded their habitats, complicating our ability to understand health impacts after a spill. This time, however, was different.

“Orcas (killer whales) have been particularly interesting because they have been so well studied and are one of the few critters for which pre-spill information was available,” NOAA biologist Gary Shigenaka says of the 1989 Exxon Valdez spill, which he has worked on extensively.

The two killer whale pods unlucky enough to swim in or near Exxon oil were from two different eco-types of killer whales, known as “resident” and “transient.”  Eco-types differ in several aspects of morphology (shape and structure), ecology, behavior, and genetics.  For example, resident whales primarily feed on fish while transient killer whales feed on marine mammals.

Since the 1989 oil spill, scientists have followed closely the killer whale populations of Southeast Alaska. They have examined both the two pods of whales exposed to the oil in Prince William Sound as well as the other resident and transient pods which were not in the oiled areas at the time. The differences are stark.

Killer whales swimming alongside boats skimming oil from the Exxon Valdez oil spill.

Killer whales swimming in Prince William Sound alongside boats skimming oil from the Exxon Valdez oil spill (State of Alaska, Dan Lawn).

In the year and a half after the Exxon Valdez spill, both groups of killer whales swimming through Prince William Sound at the time experienced an unprecedented high number of deaths. The pod of resident killer whales lost 33% and the pod of transients 41% of their populations, according to a 2008 study by researcher Craig Matkin [PDF]. In general, killer whales tend to have very stable populations, usually losing only very young or very old whales when they lose any.

But in this case, the pods were losing a number of immature whales and breeding females as well. Missing these key members, the populations in the oiled areas were slow to bounce back, if they bounced at all. One pod of resident killer whales still hasn’t reached its pre-spill numbers, while the oil-exposed transient pod’s numbers have dropped so much that NOAA’s National Marine Fisheries Service has listed them as a “depleted stock” under the Marine Mammal Protection Act. Meanwhile, the other killer whale populations in Southeast Alaska have been growing since the mid-1980s.

Graph of killer whale populations exposed to oil after the Exxon Valdez spill.

Population trends in killer whales before and after the Exxon Valdez oil spill: AB Pod is the group of resident whales while AT1 is the transient group exposed to oil in Prince William Sound. Courtesy of Craig Matkin.

Still, because researchers were unable to examine either live or most of the dead whales after the spill (and thus confirm oil-related injuries), any direct link between the spill and killer whale health has been circumstantial. Even so, Shigenaka personally believes that this indirect evidence “stands the test of time.”

The crux of it lies in the fact that two pods of very different killer whale groups crashed suddenly and simultaneously after only one obvious disturbance to their environment—the Exxon Valdez oil spill.

Fast forward twenty-one years to April 2010 in the Gulf of Mexico. Taking these lessons about killer whales and oil from the Exxon Valdez, NOAA’s Office of Response and Restoration quickly partnered up with the NOAA Fisheries Service to do reconnaissance during the Deepwater Horizon/BP oil spill, especially in oiled areas. Twenty-one species of marine mammals live in the Gulf, and bottlenose dolphins in particular potentially could be suffering some significant impacts from this spill.

Since February 2010 (before the oil spill), nearly 700 bottlenose dolphins and other species of cetaceans (dolphins and whales) in the Northern Gulf of Mexico have been stranded. These marine mammals are experiencing what’s known as an “unusual mortality event,” defined as “a stranding that is unexpected, involves a significant die-off of any marine mammal population, and demands immediate response.” Federal and state agencies have been investigating this large die-off and any possible connections to its overlap with the Deepwater Horizon/BP oil spill.

These investigations are ongoing and the possible role of infection in these dolphins adds a twist that leaves us with plenty of questions still to answer. Nevertheless, every piece of information we learn helps create a fuller picture of how oil spills affect marine mammals, whether we’re looking at killer whales in Prince William Sound or bottlenose dolphins in the Gulf of Mexico.

For more information on killer whales and the Exxon Valdez oil spill, check out:

Matkin, C.O., Saulitis, E.L., Ellis, G.M., Olesiuk, P., Rice, S.D. 2008. Ongoing population-level impacts on killer whales Orcinus orca following the ‘Exxon Valdez’ oil spill in Prince William Sound, Alaska. Marine Ecology Progress Series, 356:269-281.

Loughlin, T. R. Ed. Marine Mammals and the Exxon Valdez. Academic Press, San Diego, 1994.


NOAA Flexes Mussels for Tracking Pollution

This is a post by Gunnar Lauenstein at NOAA’s Center for Coastal Monitoring and Assessment.

Zebra mussel sampling in the the Great Lakes.

NOAA researchers Cliff Cosgrove and Gunnar Lauenstein collect samples of zebra mussels in the Great Lakes by using an epibenthic dredge. Credit: Andrew Yagiela (NOAA GLERL).

Mussels and oysters are a great natural tool for finding pollutants in the environment because they filter tiny food bits—along with fine pollutants—out of the surrounding water. They are capable of concentrating contaminants in their body tissues at levels up to 100,000 times above those in the water. This makes our job easier when we’re trying to determine whether those contaminants pose a threat to human health.

These useful traits of shellfish led the U.S. Environmental Protection Agency (EPA) to start the first two national Mussel Watch programs. In 1965, the EPA began collecting mussels and oysters from around the U.S. to determine where pesticides such as DDT [leaves this blog] were concentrated in the environment. The second national program, funded by the EPA from 1976-1978, built on that previous work but broadened the list of pollutants studied to include trace elements, oil-related compounds, and radionuclides.

Analyzing mussel tissue samples at the lab.

Researchers at the TDI-Brooks lab in College Station, Texas performing a silica and alumina cleanup of tissue samples collected through the Mussel Watch Program. Credit: Brad Bernard.

I’ve been involved with the NOAA Mussel Watch Program since NOAA took over from the EPA in 1986. I’m responsible for sample collection, methods documentation, and program direction.

Collecting mussels in New York Harbor after the events of Sept. 11, 2001.

NOAA researcher Gunnar Lauenstein and Todd Chamberlin, TDI-Brooks, collecting mussels in the rocks around Governor’s Island in New York Harbor during December 2001, three months after the attack on the World Trade Center. Credit: Roger Fay (TDI-Brooks).

The NOAA program expanded the 100 or so original EPA sample sites to more than 300 current sites. The additional sites increased the density of the areas covered in the Mussel Watch Program, particularly in Alaska and California. Starting in 1992, the program also expanded its range by sampling the infamous non-native zebra mussels in the Great Lakes.

Initially, NOAA intended to use the Mussel Watch Program to study how effective environmental management activities were as a result of 1970s-era legislation. The NOAA Mussel Watch Program successfully documented and tracked decreases of the pollutants DDT and polychlorinated biphenyls (PCBs) [leaves this blog] across the country through at least 2005. Since then, NOAA has added new contaminants to the watch list and also describes the overall health of the organisms being collected for study.

In recent years, the Mussel Watch Program has increased its collaboration both in and outside of NOAA in response to disasters by helping to determine the extent of environmental change. The program sampled New York Harbor after the events of 9/11 [PDF], after the passage of Hurricanes Rita and Katrina along the Gulf Coast [PDF, pg. 23], and more recently before, during, and after the Deepwater Horizon/BP oil spill. The Office of Response and Restoration uses this data to help determine the effects of oil spills on the environment, comparing the levels of oil compounds found before and after spills. This helps zero in on hotspots for cleanup.

Mussel Watch stations in the Gulf of Mexico

Each mussel symbol shows where Mussel Watch sampled in the Gulf of Mexico before and after the 2010 Deepwater Horizon/BP oil spill. Click for larger view. Source: NOAA.

In addition to the national Mussel Watch programs, the concept has also expanded to regional and local levels, such as in Snohomish County, Wash. [leaves this blog], as well as across Washington state [leaves this blog], where Office of Response and Restoration ecologist Alan Mearns has helped bring in citizen scientists to sample mussels for pollutants such as flame retardants along the Washington coast. NOAA has expanded this level of collaboration to include most of the coastal states. States and other local organizations are now responsible for collecting samples and making recommendations about where new study sites need to be established. As a result, local citizens and state agencies are taking more ownership of the pollution data in their areas.

If you’re interested in learning more about NOAA’s Mussel Watch Program or other research happening at NCCOS, I’ll be blogging at the Coastal Ocean Science Blog at

Gunnar Lauenstein.

Gunnar Lauenstein takes a break during sampling in the Great Lakes. Credit: NOAA/COAST Branch.

Gunnar Lauenstein is Acting COAST Branch Chief at NOAA’s National Centers for Coastal Ocean Science Center for Coastal Monitoring and Assessment [leaves this blog]. Dr. Lauenstein leads NOAA’s Mussel Watch Program [leaves this blog] at NCCOS and led a team of researchers to sample and collect mussels and oysters throughout the Gulf region before, during, and after the Deepwater Horizon/BP oil spill. You can contact him at

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A DDT Legacy and the Road to Recovery in California

This is a post by Gabrielle Dorr, NOAA/Montrose Settlements Restoration Program Outreach Coordinator.

Effects of DDT on bird eggs.

On display at the National Museum of American History, you can see the effects of DDT on a bird egg (right). Credit: Kari Bluff, Creative Commons.

If you ask the earlier Baby Boomer generation about DDT (dichlorodiphenyltrichloroethane), they might recall images of this chemical being sprayed in their neighborhoods right where they were playing.

DDT was first considered a wonder chemical by many for its use against disease-carrying insects and agricultural pests, prompting a Nobel Prize for its discovery. DDT was widely used as a pesticide beginning in the 1940s, until concerned biologists led by Rachel Carson, documented its harmful effects on birds, other wildlife, and possibly human health.

Another trait of DDT is that once released, it stays in the environment for a very long time.  The U.S. Environmental Protection Agency (EPA) finally banned its use in 1972. However, releases of this chemical were widespread by the time it was banned.

The story in southern California, however, is a little different.  A DDT manufacturing company called the Montrose Chemical Corporation, located in Torrance, Calif., had a permit to release their DDT waste through an outfall pipe that led to the ocean nearby. Other factories in the area were manufacturing PCBs, another harmful chemical, and releasing their waste through the same outfall pipe at White Point.

Millions of pounds* later, local and federal governments determined that the release of these chemicals was a violation of the Comprehensive Environmental Response Compensation Liability Act (CERCLA), which is also known as Superfund. After 10 years of litigation and data collection, a settlement agreement was reached, and funds were made available to clean up the contamination site at the bottom of the ocean along Palos Verdes Shelf and to restore resources harmed from the pollution within the Southern California Bight.

One year after a settlement was reached, in 2001, the Montrose Settlements Restoration Program (MSRP) was formed to oversee restoration of resources harmed by DDT and PCBs including Bald Eagles, Peregrine Falcons, seabirds, fishing, and fish habitat. This year marks the 10 year anniversary for the restoration program, and there is plenty to celebrate. At, you can find the program’s restoration accomplishments, photos, wildlife webcams, and the latest updates from the program’s trustee council. Relive some highlights of successful restoration milestones of the program over the last decade, and see what projects MSRP is proposing in the Draft Phase 2 Restoration Plan released for public comment this month.

A larger symbol of the hope for recovery here manifests itself in the film Return Flight: Restoring the Bald Eagle to the Channel Islands, directed by the Filmmakers Collaborative SF. This film captures the spirit of biologists, partners, volunteers, and concerned citizens working to secure a biological legacy for the Bald Eagle in southern California despite the chemical legacy of DDT.

You can watch the short film here:

*Correction: Previously, this incorrectly stated “hundreds of millions of tons,” not pounds, of PCBs and DDT waste.

Above photo is licensed under a Creative Commons Attribution-No Derivatives license.

Gabrielle Dorr

Gabrielle Dorr.

Gabrielle Dorr is the Outreach Coordinator for the Montrose Settlements Restoration Program as part of NOAA’s Restoration Center. She lives and works in Long Beach, California where she is always interacting with the local community through outreach events, public meetings, and fishing education programs.

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Four Years and $44 Million Later: Restoring San Francisco Bay After the Cosco Busan Oil Spill

This is a post by Greg Baker, a scientist with NOAA’s Office of Response and Restoration.

Cosco Busan ship with Bay Bridge.

The M/V Cosco Busan leaves the San Francisco Bay on Dec. 20, 2007, after hitting the Bay Bridge on Nov. 7. Credit: Jonathan R. Cilley, U.S. Coast Guard.

The infamous fog of San Francisco was thick and gray the morning the Cosco Busan cargo ship crashed into the San Francisco-Oakland Bay Bridge. It was November 7, 2007, and within seconds of the crash, 53,000 gallons of fuel oil were released into the surrounding waters. One of the largest oil spills in the history of San Francisco Bay, it set into motion a series of events that ultimately led to this week’s historic $44.4 million settlement [PDF] with the companies responsible for the spill (Regal Stone Limited and Fleet Management Limited).

To the public, this $44.4 million means there will be money for bird, fish, and habitat restoration in the bay. It will enhance shoreline parks and outdoor recreation throughout the Bay Area, helping compensate the public for the lost visits to the beach when oil washed up on the shores. This settlement will resolve all outstanding legal claims for natural resource damages, paying for the damage assessment, remaining cleanup costs, and for restoration of natural resources from the spill.

That first morning, we didn’t really know how much oil had been spilled—initial reports indicated it was only a small amount. But as the fog lifted, it quickly became apparent that oil was spreading over a large expanse of the bay. When I got the initial call about the spill, I had just landed in southern California to work on my major project at the time, which would soon be pushed aside. My coworker on the phone suggested I get back to the Bay Area as soon as possible. For the next several weeks I worked long hours alongside fellow scientists to quickly organize and conduct the field work to evaluate natural resource damages from the Cosco Busan oil spill.

Cosco Busan with Coast Guard boat.

A U.S. Coast Guard boat approaches the gash in the side of the Cosco Busan, which released 53,000 gallons of bunker oil into San Francisco Bay. Credit: U.S. Coast Guard.

The type of oil that gushed into San Francisco Bay was bunker oil, which is commonly used to propel large ships and is different from crude oil or refined fuels. Bunker fuels are so viscous (thick and slow-moving) that they actually have to be heated to over 100 degrees Celsius (212 degrees Fahrenheit) in order to flow to ship engines.

As the thick bunker oil spread on the waters surrounding San Francisco, it turned into tarry patches and balls that eventually stranded along hundreds of miles of shoreline. Much of our understanding about the toxic effects from oil spills comes from studies of crude oil, conducted after the 1989 Exxon Valdez spill. But as we studied the effects of bunker oil on fish and wildlife after the Cosco Busan spill, we discovered bunker oil not only behaves differently than crude oil in the environment, but it appears to have different toxicological effects.

Two to three months after the spill, when the huge annual schools of Pacific herring entered San Francisco Bay to find their shallow spawning grounds, most of the evidence of lingering bunker oil was already gone, either cleaned up or weathered away. But when we collected herring eggs from areas both affected and unaffected by the spill, we made a remarkable discovery: Almost all of the eggs collected from spill locations were dead or deformed. The eggs collected outside of the spill zone were largely normal. This was especially surprising given the lack of significant remaining evidence of bunker oil.

We conducted additional studies over two more seasons of herring spawning in the bay and eventually concluded that the toxic characteristics of the bunker oil from the Cosco Busan spill affected as much as a quarter of the herring spawning in 2008. We also concluded that the effects didn’t carry over past that first spawning season after the spill. Our studies, directed by scientists from NOAA’s Northwest Fisheries Science Center and the Bodega Marine Laboratory in California, forged new scientific understandings on the effects of oil spills on aquatic resources and will guide further progress on our assessment of present and future spills.

This week at the announcement of the $44.4 million spill settlement, I had a moment to reflect on the countless hours of work that culminated in that press conference and the road to restoration of San Francisco Bay: from the emergency responders cleaning up the oiled waters (and the thank-you cards to them from local school kids left on the beach) to the attorneys poring over the maritime and clean water laws violated by the spill.

Just two short hours before the press conference we still hadn’t received word that the settlement was filed in court. But then the message came, the last piece of the puzzle finally fell into place, and we were ready to unveil the whole, hopeful picture to the public.

The draft Damage Assessment and Restoration Plan for the Cosco Busan oil spill provides details on the restoration projects being planned; you can review it here. The public may submit comments on the plan through October 31, 2011.

Greg BakerGreg Baker works as an Environmental Scientist in the Assessment and Restoration Division of NOAA’s Office of Response and Restoration and is based in the San Francisco Bay Area.