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Do Bigger Oil Spills Require More Restoration?

This is a post by NOAA intern Franziska Economy.

Quick, can you name ten major oil spills?

Having a hard time? Until recently, I would have been scratching my head after:

  1. Deepwater Horizon/BP spill in the Gulf of Mexico (2010)
  2. Exxon Valdez tanker spill in Alaska (1989)
  3. … ?

Maybe some of you managed to come up with a couple of the other major spills from the last few decades, but this seems to be a tall order for the average person.

Oil spills actually happen just about every day, but most don’t make the news. I was surprised to learn that there are nearly 14,000 oil and chemical spills reported to the National Response Center every year.

Even crazier to me was the discovery that sometimes the best recovery option for small oil spills is actually taking “No Action.” This can be the case when cleaning up the oil would cause more harm to a sensitive ecosystem than just leaving it there to break down naturally. Sometimes, however, an oil spill can be relatively large and present real dangers to the plants and animals in the area without attracting much attention from the greater public.

Learning all of this prompted me to delve into the treasure trove of information on the oil spill cases NOAA’s Office of Response and Restoration handles. As the lead science agency for oil spills, NOAA is asked to respond to about 100–200 of the more significant marine and coastal spills every year to provide scientific support to help with the cleanup. A much smaller subset of those spills require a legal assessment of environmental monetary damages to restore those natural resources. This is known as a Natural Resource Damage Assessment or NRDA.

When studying these NRDA spill cases, I focused on two particularly interesting factors: the size of the oil spill and the “restoration cost,” or how much money the oil spiller has to pay to restore the public’s injured natural resources. Take a look at the top ten oil spill cases in each category and see how they compare:

Graph of the top ten NOAA oil spill NRDA settlements by dollar amount needed to restore injured environmental resources.

Figure 1. The top ten NOAA oil spill NRDA settlements by dollar amount needed to restore injured environmental resources. Note: each color in this graph corresponds to a spill found on both Figure 1 and Figure 2; gray spills are only found on one graph. Source: Click to enlarge.

Graph of the top ten NOAA oil spill NRDA settlements by the volume of oil spilled in gallons.

Figure 2. The top ten NOAA oil spill NRDA settlements by the volume of oil spilled in gallons. Source: Click to enlarge.

Right off the bat, it is easy to spot that bigger oil spills don’t always result in the highest restoration costs, and even if the restoration cost of a spill is relatively high, it is not necessarily related to the size of the spill. The Cosco Busan and Athos place first and second among oil spill settlements by restoration cost (Figure 1), but they are not big enough to land in the top ten by spill size (Figure 2; they are 12 and 23, respectively).

Furthermore, before the Deepwater Horizon/BP incident, the spill Barge Morris J. Berman was the largest spill that OR&R had responded to; yet it ranked only the fifth highest among restoration settlements, not even one-third the amount of the highest settlement, the Cosco Busan. In general, only half of the spills on each graph appear on the other, showing a lower correlation between these two variables than I originally thought.

So, why do you think that is? I’ve been brainstorming what factors could influence why gallons of oil spilled do not necessarily result in the most money required to restore natural resources. A single variable—such as the amount or type of oil spilled—isn’t by itself an accurate indicator of how much money it takes to respond to, clean up, and restore the environment after an oil spill. We have to examine a variety of factors to understand the bigger picture.

Other factors which might affect the restoration cost of an oil spill include:

  • the properties of the oil spilled (was it thick like tar that would sink to the bottom? Or was it light and likely to evaporate quickly from the water’s surface?)
  • the type and effectiveness of cleanup methods (was very little oil able to be recovered?)
  • the type of ecosystem affected (was it an estuary full of sensitive marsh grass and bird nesting sites or in an lower quality industrial area with a bulkheaded shoreline?)
  • the cultural and economic values of nearby cities and towns (was the spill close to a population with strong ties to the outdoor environment?)

What other issues do you think might play a role in how much restoration is required to offset the impacts of an oil spill on the environment?

Franziska Economy is an American University graduate with a Bachelors of Arts in Economics and Environmental Science. She is working as a Constituent and Legislative Affairs intern for NOAA’s Office of Response and Restoration and enjoys sharing the interesting facts she has learned and statistics she has uncovered. She hopes to help break down the acronym-filled, complicated world of responding to oil spills, assessing damages, and restoring broken ecosystems.