Nearing the six-month mark after the Deepwater Horizon explosion, the federal government’s top responders to the Gulf of Mexico oil spill are reporting on-the-water findings that couldn’t have been imagined at the height of the crisis four months ago: very little recoverable oil still in the water or on the bottom, barely even trace amounts of dispersant chemicals and no samples of contaminated seafood in open water or in the marshes.
The assessment from the federal on-scene coordinator, Coast Guard Rear Adm. Paul Zukunft, and science adviser Steve Lehmann comes as the number of responders to the oil spill in the Gulf still remains at nearly 13,500 — a sharp decrease from the maximum of 48,000 this summer, but a number that still outpaces the 11,000 peak responders for the Exxon Valdez spill in 1989.
In an interview with The Times-Picayune Monday, Zukunft and Lehmann did not downplay areas along the Louisiana coast that are still major hotspots for cleanup operations. Bay Jimmy in Barataria Bay, west of Port Sulphur, still has crew of more than 600 responders cleaning up areas of marsh that were heavily impacted over the past few months, as tidal movements continue to bring residual oil in contact with the marsh.
Areas near the mouth of the river such as Pass a Loutre and South Pass are also seeing continual impacts.
But the federal response officials pointed out that aside from a few areas of lingering oil, responders are not finding significant or even measurable amounts of oil or dispersants in the water column or in sediments on the water bottom.
At the opening of white shrimp season in mid-August, Zukunft said he sent a fleet of eight shrimp trawlers outfitted with absorbent boom dragging the water bottom to collect oil and tar balls.
“We trawled for over 10 days trying to catch tar balls, and in all those trawls that we made we caught one tar ball,” Zukunft said. Responders have also placed nearly 500 “sentinel snares” — essentially crab traps loaded with boom suspended from the surface to the bottom.
“We’ve got literally tens of thousands of data points in that nearshore environment, and in that one area where did find oil it was in close proximity to where we had oiled marsh,” Zukunft said.
The findings tend to defy popular assumptions that the oil may have sunk to the bottom, and also run counter to anecdotal reports from fishers who say they have seen oil in nets or on the bottom of bays and marshes.
Samantha Joye, a professor of marine sciences at the University of Georgia, also reported findings last month from her research vessel in the Gulf that indicated a layer of oil at the bottom of the sea near the Deepwater Horizon wellhead.
Lehmann, who is a scientific support coordinator with the National Oceanic and Atmospheric Administration, said that Joye’s findings were preliminary and that the government and other researchers are testing in similar areas.
“We have, to date, not found anything that is: one, unexpected; two, particularly alarming; and three, that is recoverable,” Lehmann said.
As for the idea that vast quantities of the oil are sinking instead of evaporating or being consumed by microorganisms, Lehmann said Monday that the characteristics of the light crude oil from the Macondo well would not allow it to sink in large quantities in salt water.
“Even when it gets very old, even when a lot of it evaporates, it doesn’t get to a point where it wants to sink,” Lehmann said. “It’s very light, in fact I don’t know that we know of a crude oil that sinks in salt water. There are refined oils that do that, but with crude oils I can’t think of one.
“So the concept of a big slick of oil sinking to the bottom is kind of an anathema. We have not found anything that we would consider actionable at 5,000 feet or five feet.”
Aside from heavily impacted areas such as Bay Jimmy, Zukunft said most of the concentrations of oil and dispersants found in the water are incredibly low, on the level of half a part per billion.
“Keep in mind that if we’re finding a half a part per billion at the highest, we wouldn’t be able to recover in the water column itself at parts per 10,” Lehmann said. “It’s like trying to get cream out of your coffee, we just don’t do it. There’s a limitation to what we can do in terms of mitigating the oil in the environment.”
For dispersant chemicals, which are water soluble and tend to break down quickly, Lehmann also said the findings have been encouraging. “We’re not seeing anything that’s alarming, that’s going over any of the benchmark standards that we’ve got.”
Along beaches in Alabama, Mississippi and Florida, machines known as “sand sharks” are combing through miles of sand beaches where layers of oiled sand may be deposited below the surface, separating the clean sand from tar-like layers.
Both officials differentiated, however, between what can be done with the immediate clean-up response and what will eventually be done for the long-term natural resource damage assessment process. That interagency process literally assigns damage costs to various habitats and plant and animal life impacted by the spill, tallying up the costs that will be paid by BP to state and federal resource agencies.
It’s in that process where officials will attempt to address the biggest unknowns: the extent of damage to bluefin tuna, which has spawning grounds offshore in the area of the wellhead, and other species whose spawn may have been impacted by oil or dispersants.
“What this doesn’t address is at the very lowest end of the food chain, what long-term effect might it have as it works its way through the food chain over a period of several years,” Zukunft said. “Right now we’re not seeing any indications of any of the commonly known species at risk because of this spill, but that will have to continue under the (NRDA) process.”
