NOAA's Response and Restoration Blog

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


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A Final Farewell to Oil Tankers with Single Hulls

January 1, 2015 marks a major milestone in preventing oil spills. That date is the deadline which the landmark Oil Pollution Act of 1990 (OPA-90) specifies for phasing out single-hull tankers in U.S. waters. That act, passed after the 1989 Exxon Valdez oil spill in Prince William Sound, Alaska, required that all new tankers and tank-barges be built with double hulls.

Recently constructed single-hull tankers were allowed to operate, but 25 years after the Exxon Valdez, those vessels are now at the end of their operational life and will no longer be able to carry oil as cargo. The requirement was phased in gradually because of the difficultly of converting existing single-hull tankers to double hulls, and retiring the single-hull tankers more rapidly would have been a major disruption to world shipping.

Counting Down to a New Era

There won’t be a dramatic change-over on New Year’s Eve; most of the tankers calling on U.S. ports have had double hulls years before this deadline. However, one ship which was not switched over to a double hull soon enough was the tanker Athos I. This ship, carrying 13.6 million gallons of heavy crude oil, struck a submerged anchor in the Delaware River and caused a relatively large, complicated oil spill near Philadelphia, Pennsylvania, 10 year ago.

In 1992, two years after the Oil Pollution Act, the International Convention for the Prevention of Pollution from Ships (the MARPOL Convention) was amended to require all newly built tankers have double hulls. MARPOL has been ratified by 150 countries, representing over 99 percent of merchant tonnage shipped worldwide.

Stay out of Trouble by Going Double

So, what is the big issue around single vs. double-hull ships? Historically, tankers carrying oil were built with a single hull, or single shell.

While we measure oil in barrels, it is not actually shipped that way. Instead, oil is pumped into huge tanks that are part of the structure of tankers and barges. For vessels with a single hull, one plate of steel is all that separates the oil on board from the ocean. If the hull were punctured from a collision or grounding, an oil spill is pretty much guaranteed to follow. On the other hand, a ship with a double hull has two plates of steel with empty space in between them. The second hull creates a buffer zone between the ocean and the cargo of oil.

Naval architects have debated the merits of various hull designs in reducing oil spills, and using a double hull, essentially a hull within a hull, was selected as the preferred vessel design.

Close up of gash in hull on Cosco Busan cargo ship.

The cargo ship Cosco Busan lost 53,000 gallons of fuel oil when the single-hull ship hit the San Francisco-Oakland Bay Bridge in 2007. (U.S. Coast Guard)

However, the double hull requirements only apply to tankers and tank barges. Container ships, freighters, cruise ships, and other types of vessels are still built with single hulls. While these ships carry a lot less oil than a tanker, a large non-tank vessel can still carry a lot of fuel oil, and some have caused some pretty big spills, including the 2007 oil spill caused by the cargo ship Cosco Busan in San Francisco Bay.

Of course, double hulls don’t prevent all oil spills from tankers either, but the design has been credited with reducing the amount spilled, especially in the cases of low-speed groundings and collisions.

And some pretty spectacular collisions have resulted in double-hull tankers not spilling a drop.

Twenty years after the Exxon Valdez oil spill, the Norwegian tanker SKS Satilla collided with a submerged oil rig in the Gulf of Mexico. The collision tore a huge hole in the side of the oil tanker, but, thankfully, none of the 41 million gallons of crude oil it had on board was spilled.


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NOAA Prepares for Bakken Oil Spills as Seattle Dodges Oil Train Explosion

As federal leaders in oil spill response science, NOAA’s Office of Response and Restoration is grateful for each oil spill which does not take place, which was fortunately the case on July 24, 2014 in Seattle, Washington, near our west coast office. A train passing through the city ran off the tracks, derailing three of its 100 tank cars carrying Bakken crude oil from North Dakota to a refinery in the port town of Anacortes, Washington. No oil spilled or ignited in the accident.

However, that was not the case in five high-profile oil train derailments and explosions in the last year, occurring in places such as Casselton, North Dakota, when a train carrying grain derailed into an oil train, causing several oil tank cars to explode in December 2013.

Oil production continues to grow in North America, in large part due to new extraction technologies such as hydraulic fracturing (fracking) opening up massive new oil fields in the Bakken region of North Dakota and Montana. The Bakken region lacks the capacity to transport this increased oil production by the most common methods: pipeline or tanker. Instead, railroads are filling this gap, with the number of tank cars carrying crude oil in the United States rising more than 4,000 percent between 2009 (9,500 carloads) and 2013 (407,761).

Just a day before this derailment, Seattle City Council signed a letter to the U.S. Secretary of Transportation, urging him to issue an emergency stop to shipping Bakken crude oil in older model tank train cars (DOT-111), which are considered less safe for shipping flammable materials. (However, some of the proposed safer tank car models have also been involved in oil train explosions.) According to the Council’s press release, “BNSF Railway reports moving 8-13 oil trains per week through Seattle, all containing 1,000,000 or more gallons of Bakken crude.” The same day as the Council’s letter, the Department of Transportation proposed rules to phase out the older DOT-111 model train cars for carrying flammable materials, including Bakken crude, over a two-year period.

NOAA’s Office of Response and Restoration is examining these changing dynamics in the way oil is moved around the country, and we recently partnered with the University of Washington to research this issue. These changes have implications for how we prepare our scientific toolbox for responding to oil spills, in order to protect responders, the public, and the environment.

The fireball that followed the derailment and explosion of two trains, one carrying Bakken crude oil, on December 30, 2013, outside Casselton, N.D.

The fireball that followed the derailment and explosion of two trains, one carrying Bakken crude oil, on December 30, 2013, outside Casselton, N.D. (U.S. Pipeline and Hazardous Materials Safety Administration)

For example, based on our knowledge of oil chemistry, we make recommendations to responders about potential risks during spill cleanup along coasts and waterways. We need to know whether a particular type of oil, such as Bakken crude, will easily ignite and pose a danger of fire or explosion, and whether chemical components of the oil will dissolve into the water, potentially damaging sensitive fish populations.

Our office responded to a spill of Bakken crude oil earlier this year on the Mississippi River. On February 22, 2014, the barge E2MS 303 carrying 25,000 barrels of Bakken crude collided with a towboat 154 miles north of the river’s mouth. A tank of oil broke open, spilling approximately 31,500 gallons (750 barrels) of its contents into this busy waterway, closing it down for several days. NOAA provided scientific support to the response, for example, by having our modeling team estimate the projected path of the spilled oil.

Barge leaking oil on a river.

Barge E2MS 303 leaking 750 barrels of Bakken crude oil into the lower Mississippi River on February 22, 2014. (U.S. Coast Guard)

We also worked with our partners at Louisiana State University to analyze samples of the Bakken crude oil. We found the oil to have a low viscosity (flows easily) and to be highly volatile, meaning it readily changes from liquid to gas at moderate temperatures. It also contains a high concentration of the toxic components known as polycyclic aromatic hydrocarbons (PAHs) that easily dissolve into the water column. For more information about NOAA’s involvement in this incident, visit IncidentNews.


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Protecting the Great Lakes After a Coal Ship Hits Ground in Lake Erie

The coal ship CSL Niagara got stuck in Lake Erie's soft, muddy bottom at the entrance to Sandusky Bay in November 2013.

The coal ship CSL Niagara got stuck in Lake Erie’s soft, muddy bottom at the entrance to Sandusky Bay in November 2013. (U.S. Coast Guard)

In the course of a year, from October 2012 to October 2013, the Emergency Response Division of NOAA’s Office of Response and Restoration responded to 138 oil spills, chemical accidents, and various other threats to coastal environments and communities. Many of these responses required considerable time from the scientific team to estimate where spills might spread, analyze chemical hazards, and assess whether natural resources are at risk. Sometimes, however, we’re called into some incidents that end well, with minimum help needed on our part and no oil spilled.

Last November, LCDR John Lomnicky received a call from the U.S. Coast Guard with an example of an accident that had the potential to be much worse. LCDR Lomnicky is our Scientific Support Coordinator for the Great Lakes region and is based in Cleveland, Ohio.

When Staying Grounded Is a Bad Thing

On November 17, just after 10:00 in the morning, the vessel master of the CSL Niagara reported to the U.S. Coast Guard that his ship had run aground while leaving Sandusky Bay through Moseley Channel to Lake Erie. Aboard the ship were 33,000 metric tons (36,376 U.S. tons) of coal, headed to Hamilton, Ontario, and about 193 metric tons of intermediate fuel oil (a blend of gasoil and heavy fuel oil) and marine diesel. The concern in a situation like this would be that the grounded ship might leak oil. Its stern was stuck in the soft mud at the bottom of Lake Erie. At the time, the vessel master reported there were no injuries, flooding, or visible pollution.

This ship, the CSL Niagara, has a long history of transporting coal in Lake Erie. Launched in April of 1972 for Canada Steamship Lines, Ltd., the new ship was 730 feet long and even then was carrying coal to Hamilton, Ontario. During over 40 years of sailing in the Great Lakes, the Niagara has also carried cargos of grain, coke, stone, and iron ore.

NOAA chart of Lake Erie.

Lake Erie has an average depth of 62 feet, but its western basin, where the CSL Niagara grounded, averages only 24 feet deep. (NOAA Chart)

Even though the vessel hadn’t released any oil, the Coast Guard Marine Safety Unit, who had responders at the scene very shortly after the accident, put in a call to the Office of Response and Restoration’s LCDR Lomnicky for scientific support. As a precaution, they requested that we model the trajectory of oil in a worst case scenario if 145 metric tons of intermediate fuel oil and 48 metric tons of diesel fuel were released all at once into the water. We also provided a prediction of when the lake’s lower-than-usual water level would return to normal so a salvage team could refloat the stuck vessel. After gathering all of this information for the Coast Guard, LCDR Lomnicky continued to stand by for further requests.

In the hours that followed the ship’s grounding, the winds grew stronger, hampering efforts to free the vessel. The wind was causing the water level in the lake to drop and NOAA’s National Weather Service in Detroit predicted a 7.5 foot drop in levels for western Lake Erie. By 8:30 p.m., with 30 knot winds in two-to-three foot seas, the three tugboats contracted by the ship’s owner to dislodge the Niagara were making some progress. By midnight, however, with weather conditions worsening, salvage operations were suspended and scheduled to resume at first light.

But the next morning, November 18, the water level had dropped another two feet, and the three tugs still had had no luck freeing the stern of the Niagara from the lake bottom. The ship’s owner was now working on plans for lightering (removing the fuel) and containing any potentially spilled oil. Fortunately, there were still no reports of damage to the vessel or oil discharged into the water. The ship was just stuck.

By 4:00 that afternoon the water conditions had improved and another attempt to free the vessel was planned. Also, a combined tug-barge was en route should lightering become necessary.

Later that evening, shortly after 10:00, the ship was pulled free by two of the tugs and was back on its way early the next morning.

The location where the CSL Niagara grounded in Lake Erie is indicated with a red diamond, along with a window of information and photo of the grounded ship. It is mapped in Great Lakes ERMA, NOAA's online mapping tool for coastal pollution cleanup, restoration, and response.

The location where the CSL Niagara grounded in Lake Erie is indicated with a red diamond, along with a window of information and photo of the grounded ship. It is mapped in Great Lakes ERMA, NOAA’s online mapping tool for coastal pollution cleanup, restoration, and response. (NOAA)

Keeping the Great Lakes Great

Lake Erie is the shallowest of the five Great Lakes, with an average depth of 62 feet. Yet its western basin, where this ship grounding occurred, has an average depth of only 24 feet. The lake is an important source of commerce for both the U.S and Canada, who depend on it for shipping, fishing, and hydroelectric power. These industries place environmental pressure on the lake’s ecosystems, which  are also threatened by urban and agricultural runoff.

Happily, quick responders, sound information, and a break in the weather may have prevented this incident from becoming something much worse. A spill into Lake Erie could be devastating, especially considering its shallow waters, but this time, like many other times along the nation’s coasts, an oil spill was avoided.

Didn’t know that NOAA works in the Great Lakes? Nicknamed “the third coast,” the Great Lakes are a major U.S. water body, with a shoreline that stretches longer than the East Coast and Gulf Coast combined. Learn more about the Great Lakes and NOAA’s efforts there in this Great Lakes regional snapshot.


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Study Shows Gulf Dolphins in Poor Health following Deepwater Horizon Oil Spill

A dolphin is observed with oil on its skin on August 5, 2010, in Barataria Bay, La.

A dolphin is observed with oil on its skin on August 5, 2010, in Barataria Bay, La. (Louisiana Department of Wildlife and Fisheries/Mandy Tumlin)

Barataria Bay, located in the northern Gulf of Mexico, received heavy and prolonged oiling after the 2010 Deepwater Horizon oil spill. This area is also home to many bottlenose dolphins. In the wake of the spill, how healthy are dolphins living in this area? And how do they compare to dolphins living elsewhere?

As part of the Natural Resource Damage Assessment for the Deepwater Horizon oil spill, a team of more than 50 government, academic, and non-governmental researchers assessed the health of bottlenose dolphins living in Louisiana’s Barataria Bay, which received heavy oiling following the Deepwater Horizon spill, and in Florida’s Sarasota Bay, which was not oiled following the spill.

The team of scientists and veterinarians temporarily captured live dolphins, performed comprehensive health examinations on them at the site, and then released them. The health exam included measuring each dolphin’s length and weight; doing a physical exam; sampling skin, blood, and blubber; and performing an ultrasound to evaluate their internal organs, particularly their lung condition and pregnancy status. The team has published the results of this study in the peer-reviewed journal Environmental Science & Technology.

We spoke with two of the NOAA scientists involved, Dr. Lori Schwacke and Dr. Teri Rowles, to learn more about the research and what their findings mean for dolphins in the Gulf of Mexico.

Q: When did you conduct the dolphin health assessments and what did you observe?

Aug 2011: A veterinarian performs an ultrasound to assess a Barataria Bay dolphin’s health.

Aug 2011: A veterinarian performs an ultrasound to assess a Barataria Bay dolphin’s health. (NOAA)

The first health assessments were conducted in the summer of 2011 in Barataria Bay, La., and in Sarasota Bay, Fla. We found that the dolphins in Barataria Bay were in very poor health. Many of them were underweight and their blood tests showed a number of abnormal conditions such as anemia, elevated markers of inflammation, and increased liver enzymes.

Also, one rather unusual condition that we noted in many of the Barataria Bay dolphins was that they had very low levels of some hormones (specifically, cortisol) that are produced by the adrenal gland and are important for a normal stress response. Under a stressful condition, such as being chased by a predator, the adrenal gland produces cortisol, which then triggers a number of physiological responses including an increased heart rate and increased blood sugar. This gives an animal the energy burst that it needs to respond appropriately. In the Barataria Bay dolphins, cortisol levels were unusually low. The concern is that their adrenal glands were incapable of producing appropriate levels of cortisol, and this could ultimately lead to a number of complications and in some situations even death.

We also found significant lung disease. We looked for several different abnormalities based on studies that have been done on captive animals, and what we saw was most consistent with pneumonia. In some of the animals, the lung disease was so severe that we considered it life-threatening for that individual.

Q: How serious were the conditions observed in dolphins from Barataria Bay?

Some of the conditions observed in these dolphins were very serious. Some of the animals had multiple health issues going on, such as lung disease, very high liver enzymes, and indications of chronic inflammation. The veterinarians assigned a prognosis for each animal and nearly half of the Barataria Bay dolphins were given a guarded (uncertain outcome) or worse prognosis. In fact, 17 percent of them were given a poor or grave prognosis, indicating that they weren’t expected to live.

In comparison, in Sarasota we had only one guarded prognosis and the rest were in good or fair condition. Sarasota dolphins were much healthier than Barataria Bay dolphins.

Q: Have you been able to follow up on the status of any of the dolphins examined during these assessments?

We know one of them died. Y12 was a 16-year-old male that we examined in August 2011. He was underweight and many of his blood parameters were out of the expected range. The veterinary team assigned him a grave prognosis. His carcass was recovered by the Louisiana Department of Wildlife and Fisheries in January of 2012. So we know that he only survived a little over five months  after the health assessment was conducted. . But often carcasses aren’t recovered, and there were other dolphins that we examined that we didn’t expect to live for very long.

We’re also conducting photographic monitoring studies to monitor the survival and reproductive success or failure of the dolphins we sampled. Several of the females we sampled in Barataria Bay were pregnant so we’ve been monitoring them around and past their due date to see whether or not we see them with a calf. The gestation period for a dolphin is around 12 months, so these monitoring studies take a little bit longer. We hope to report those results soon.

Q: Are the disease conditions observed in Barataria Bay dolphins—lung disease, compromised stress hormone response—consistent with those expected from exposure to oil?

The decreased cortisol response is something fairly unusual but has been reported from experimental studies of mink exposed to fuel oil. The respiratory issues are also consistent with experimental studies in animals and clinical reports of people exposed to petroleum hydrocarbons.

Q: How do you know these health impacts weren’t caused by other lingering pollutants in the Gulf?

We analyzed the dolphins’ blubber to evaluate the levels of contaminants that have been previously reported in marine mammal tissues and then also linked with health effects. This covered a fairly broad suite of contaminants and included polychlorinated biphenyls (PCBs) as well as a suite of persistent pesticides that we know accumulate in dolphins over their lifetime, leaving a record of their exposure. We found that the levels of these pollutants in Barataria Bay dolphins were actually lower than the levels in Sarasota Bay dolphins. The levels from Barataria Bay dolphins were also low compared to previously reported levels in dolphins from a number of other coastal sites in the southeastern U.S. Therefore, we don’t think that the health effects we saw can be attributed to these other pollutants that we looked at.

Q: Are there more dolphin health assessments currently taking place or planned for the future?

Yes, in the summer of 2013 we repeated the studies in Sarasota Bay and Barataria Bay and expanded the studies to Mississippi Sound, where we assessed dolphins both in Mississippi and in Alabama waters. Those samples and data are still being analyzed.

Q: Was there anything about this study that you found surprising?

The magnitude of the health effects that we saw was surprising. We’ve done these health assessments in a number of locations across the southeast U.S. coast and we’ve never seen animals that were in this poor of condition.

Q: How does this study relate to or inform the investigation of the high number of marine mammal strandings observed along the Gulf Coast since February 2010 (the Unusual Mortality Event), which pre-dates the Deepwater Horizon oil spill?

Following the Deepwater Horizon oil spill, numerous dolphins were documented encountering oil, such as those in this photo from July 2010.

Following the Deepwater Horizon oil spill, numerous dolphins were documented encountering oil, such as those in this photo from July 2010. (NOAA)

The Unusual Mortality Event that’s underway is in the same general geographic area as the Deepwater Horizon oil spill response and overlaps with the Natural Resource Damage Assessment. These findings overlap with the high number of strandings, particularly in the Barataria Bay or central Louisiana area.

When you have a significant event like an oil spill or an Unusual Mortality Event, being able to study both live and dead animals provides more information about what might be going on as animals get ill and then die. Having access to findings from both of these studies enables us to look for commonalities between what we’re finding in the sick animals and what we’re finding in the dead animals to better evaluate causes and contributing factors.

Q: Outside of NOAA, who else did you work with to perform the health assessment?

This work was part of the Deepwater Horizon Natural Resource Damage Assessment being conducted cooperatively among NOAA, other federal and state trustees, and BP. This wouldn’t have been possible without the help of a number of our partners, including the National Marine Mammal Foundation, Chicago Zoological Society, and Louisiana Department of Wildlife and Fisheries. Also, Seaworld and the Georgia Aquarium provided personnel to support our studies. Their expertise and experience were key to getting these studies done.

We greatly appreciate the efforts of researchers from the Sarasota Dolphin Research Program, which led the dolphin health assessments in Sarasota.

Watch a video of the researchers as they temporarily catch and give health exams to some of the dolphins in Barataria Bay, La., in August of 2011:


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How Do Oil Spills Affect Coral Reefs?

Coral habitat in the Hawaiian Islands.

Coral habitat in the Hawaiian Islands. (NOAA)

A warming, more acidic ocean. Grounded ships and heavy fishing nets. Coral reefs face a lot of threats from humans. For these tiny animals that build their own limestone homes underwater, oil spills may add insult to injury.

But how does spilled oil reach coral reefs? And what are the effects?

How an oil spill affects corals depends on the species and maturity of the coral (e.g., early stages of life are very sensitive to oil) as well as the means and level of exposure to oil. Exposing corals to small amounts of oil for an extended period can be just as harmful as large amounts of oil for a brief time.

Coral reefs can come in contact with oil in three major ways:

  1. Oil floating on the water’s surface can be deposited directly on corals in an intertidal zone when the water level drops at low tide.
  2. Rough seas can mix lighter oil products into the water column (like shaking up a bottle of salad dressing), where they can drift down to coral reefs.
  3. As heavy oil weathers or gets mixed with sand or sediment, it can become dense enough to sink below the ocean surface and smother corals below.

 

Oil slicks moving onto coral reefs at Galeta at low tide after the Bahia las Minas refinery spill, Panama, in April 1986.

Oil slicks moving onto coral reefs at Galeta at low tide after the Bahia las Minas refinery spill, Panama, in April 1986. (NOAA)

Once oil comes into contact with corals, it can kill them or impede their reproduction, growth, behavior, and development. The entire reef ecosystem can suffer from an oil spill, affecting the many species of fish, crabs, and other marine invertebrates that live in and around coral reefs.

As oil spill responders, NOAA’s Office of Response and Restoration has to take these and many other factors into account during an oil spill near coral reefs. For example, if the spill resulted from a ship running aground on a reef, we need to consider the environmental impacts of the options for removing the ship. Or, if an oil spill occurred offshore but near coral reefs, we would advise the U.S. Coast Guard and other pollution responders to avoid using chemical dispersants to break up the oil spill because corals can be harmed by dispersed oil.

We also provide reports and information for responders and natural resource managers dealing with oil spills and coral reefs:

You can learn more about coral reefs, such as the basic biology of corals, how damaged coral reefs can recover from an oil spill or be restored after a ship grounding, and what we’ve learned about oil spills in tropical reefs.

For lessons a little closer to home, be sure to find out five more things you should know about coral reefs and listen to this podcast about threats to coral health from NOAA’s National Ocean Service.


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NOAA Report Identifies Shipwrecks with the Potential to Pollute

On May 14, 1942, the U.S. Army Air Corps photographed the location of the burning tanker Potrero del Llano. (National Archives)

On May 14, 1942, the U.S. Army Air Corps photographed the location of the burning tanker Potrero del Llano. (National Archives)

Over the past couple years I’ve talked about the threat of oil spills from historic shipwrecks, including the S/S Edmund Fitzgerald in the Great Lakes and the S/S Montebello off southern California. But we know that these wrecks are just the tip of the iceberg.

The past century of commerce and warfare has dotted our waters with shipwrecks, many of which have never been surveyed. Since 2010, my office, working with the Office of National Marine Sanctuaries and the U.S. Coast Guard, has been systematically looking at which of these wrecks might pose a substantial threat of leaking oil still on board. This work is part of NOAA’s Remediation of Underwater Legacy Environmental Threats (RULET) project.

We used a tiered approach to develop an initial priority list of vessels for risk assessment. This process narrowed down the estimated 20,000 vessels in U.S. waters to 573 that met the initial criteria. The ships had to be over 1,000 gross tons (making them about 200 feet or longer), built to carry or use oil as fuel, and made of a durable material such as steel.

Understanding how a shipwreck site formed helps explain why vessels, like the Dixie Arrow which initially carried approximately 86,136 barrels of crude oil, but was demolished during World War II, no longer remain intact and are no longer potentially polluting shipwrecks. (NOAA)

Understanding how a shipwreck site formed helps explain why vessels, like the Dixie Arrow which initially carried approximately 86,136 barrels of crude oil, but was demolished during World War II, no longer remain intact and are no longer potentially polluting shipwrecks. (NOAA)

Additional research revealed the actual number posing a substantial pollution threat was lower because of the violent nature in which some ships sank (many were lost in World War II). This is because, for example, a ship hit and sunk by torpedoes would be less likely to still have intact tanks of oil. And other vessels were taken off our radar because they have fallen apart or were demolished because they were navigational hazards.

We also used computer models to predict the environmental and economic consequences of oil spills from these vessels. Those results then helped us sort out which wrecks might pose the biggest risks.

A map showing the name, location, and priority level of shipwrecks recommended to the U.S. Coast Guard for further pollution assessment. (NOAA)

A map showing the name, location, and priority level of shipwrecks recommended to the U.S. Coast Guard for further pollution assessment. (NOAA)

On May 20, we released both an overall report describing this work and our recommendations and 87 individual wreck assessments. The individual risk assessments highlight not only concerns about potential ecological and socio-economic impacts, but they also characterize most of the vessels as being historically significant. In addition, many of them are grave sites, both civilian and military.

The national report and the 87 risk assessments are available at http://sanctuaries.noaa.gov/protect/ppw/.


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For Submerged Oil Pollution in Western Gulf of Mexico, Restoration Is Coming After 2005 DBL 152 Oil Spill

By Sandra Arismendez, Regional Resource Coordinator for the Office of Response and Restoration’s Assessment and Restoration Division.

Imagine trying to describe the state of 45,000 acres of habitat on the ocean bottom—an area the size of over 34,000 football fields. And you have to do it without four of your five senses. You can’t touch it. You can’t taste it. You can’t smell it. You can’t hear it. Sometimes you can barely see a few inches in front of your scuba mask as you swim 60 feet below the surface in the murky waters of the Gulf of Mexico. But that was the task NOAA scientists faced seven years ago in the wake of a large offshore oil spill in the western Gulf of Mexico.

The DBL 152, shown here on November 13, 2005 shortly before capsizing, ended up discharging nearly 2 million gallons of a thick slurry oil, which sank to the floor of the Gulf of Mexico. (ENTRIX)

The DBL 152, shown here on November 13, 2005 shortly before capsizing, ended up discharging nearly 2 million gallons of a thick slurry oil, which sank to the floor of the Gulf of Mexico. (ENTRIX)

An Oily-Fated Journey

The oil was released from tank barge (T/B) DBL 152 as it was traveling from Houston, Texas, to Tampa, Fla., in November 2005.  While in transit, the barge struck the submerged remains of a pipeline service platform that collapsed a few months earlier during Hurricane Rita. The double-hulled barge was carrying approximately 5 million gallons of slurry oil, a type of oil denser than seawater, which meant as the thick oil poured out of the barge, it sank to the seafloor.

Heavy chains dragged absorbent material along the seafloor in the Gulf of Mexico in order to detect submerged oil. (ENTRIX, 11/19/2005)

Heavy chains dragged absorbent material along the seafloor in the Gulf of Mexico in order to detect submerged oil. (ENTRIX, 11/19/2005)

Eventually, the barge’s tug was able to tow it toward shore, hoping to ground and stabilize it in shallower waters. However, the barge grounded unexpectedly 30 miles from shore, releasing more oil and eventually capsizing. Approximately 1.9 million gallons of oil drained into the open waters of the Gulf of Mexico. To find, track, and clean up the oil in these cloudy waters, oil spill responders used information from divers, remotely operated vehicles (ROVs), and oil trajectory models. Executing this process over such a large area of the seafloor took more than a year. While divers were able to recover an estimated 98,910 gallons of oil, some 1.8 million gallons more remained unrecovered.

NOAA’s Damage Assessment, Remediation, and Restoration Program (DARRP) provides the unique scientific and technical expertise to assess and restore natural resources injured by oil spills like the DBL 152 incident as well as releases of hazardous substances and vessel groundings.  For more than 20 years, DARRP has worked cooperatively with other federal, tribal, and state co-trustees and responsible parties to assess the injuries and reverse the effects of contamination to our marine resources, including fish, marine mammals, wetlands, reefs, and other ocean and coastal habitats.

Oil Spill Sentinels in the Open Sea

So what happened to the other 1.8 million gallons of oil which were not feasible to clean up? Initially, the oil sank to the ocean bottom, creating a “footprint” of the impacted area.

Crab pot sentinels used to detect submerged oil on the seafloor in the Gulf of Mexico. (ENTRIX, Dec. 3, 2005)

Crab pot sentinels used to detect submerged oil on the seafloor in the Gulf of Mexico. (ENTRIX, Dec. 3, 2005)

Immediately following the spill, NOAA, the U.S. Coast Guard, Texas state trustees, and the responsible party worked together to assess impacts to natural resources and habitats affected by the spill. Scientists collected and analyzed oil samples, bottom-dwelling animals living in the sediments, and samples of sediments and water taken in the oiled areas. In particular, creatures on the seafloor were at risk of being smothered or contaminated by the dense oil as it sank to the bottom.

As you might expect, assessing injuries to an area of the open ocean covering 34,000 football fields is no easy task, especially considering how difficult it is to detect the oily culprit itself. Because we couldn’t always see the submerged oil over such a large area, oil-absorbing pads were dragged systematically across miles of ocean to locate patches of oil. Underwater sorbent “sentinels,” oil-absorbing tools used to detect oil, also were placed and monitored strategically in the predicted path of the spilled oil to tell us if the footprint of the remaining oil at the ocean bottom was relatively stationary, and if not, in what general direction it was moving. Monitoring revealed the oiled area was moving and dissipating over time as it weathered due to exposure to physical forces such as currents.

The environmental assessment showed that fish and organisms living on or near the ocean floor (such as worms, clams, and crabs) were injured by the oil that sank to the bottom of the Gulf of Mexico. That submerged oil impacted approximately 45,000 acres of ocean floor. However, much of this area recovered over time as the oil naturally dissipated and weathering broke it up.

A Path Forward

Submerged oil from Tank Barge DBL 152 on the seafloor in the Gulf of Mexico. (EXTRIX, December 2005)

Submerged oil from Tank Barge DBL 152 on the seafloor in the Gulf of Mexico. (EXTRIX, December 2005)

In March 2013, NOAA released the Damage Assessment and Restoration Plan [PDF] for the DBL 152 incident, which demonstrates that restoration is possible for this oil spill. The plan outlines injuries to natural resources and proposes a restoration project to implement estuarine shoreline protection and salt marsh creation at the Texas Chenier Plain National Wildlife Refuge Complex in Galveston Bay, Texas. The preferred shoreline protection and marsh restoration project proposed in the draft plan is designed to replenish the natural resources lost due to the oiling during the period both when they were injured and while they recovered.

Public comments can be submitted through April 15, 2013 by mailing written comments to: 

NOAA, Office of General Counsel, Natural Resources Section
Attn: Chris Plaisted
501 W. Ocean Blvd., Suite 4470
Long Beach, CA 90802

Or submitting comments electronically at www.regulations.gov (Docket I.D.:  NOAA-NMFS-2013-0034).

Following the close of the public comment period, NOAA will consider any comments and release a Final Restoration Plan. This comment period is the last step before restoration projects are selected and funding is sought from the Oil Spill Liability Trust Fund for implementation.

Since the party responsible for the oil spill reached its legal limit of liability and is not obligated to pay further liabilities by law, NOAA will submit a claim to the National Pollution Funds Center (NPFC), administered by the U.S. Coast Guard, to cover the cost of enacting the needed environmental restoration. The Pollution Funds Center serves as a safety net to help cover the costs of reclaiming our nation’s invaluable natural resources following these types of events.

Sandra Arismendez

Sandra Arismendez

Sandra Arismendez is a coastal ecologist and Regional Resource Coordinator for the Gulf of Mexico in the Assessment and Restoration Division of NOAA’s Office of Response and Restoration.