The Obama administration on Wednesday defended the integrity of estimates that turned out to be inaccurate showing how much oil spilled in the Gulf of Mexico, disclosing thousands of pages of internal e-mails written by government scientists on the project. "It is a guess," a senior U.S. scientist acknowledged to his colleagues.

The Obama administration on Wednesday defended the integrity of estimates that turned out to be inaccurate showing how much oil spilled in the Gulf of Mexico, disclosing thousands of pages of internal e-mails written by government scientists on the project. "It is a guess," a senior U.S. scientist acknowledged to his colleagues.


The behind-the-scenes e-mails hint at uncertainties in what the government knew during the summer, even as its scientists wrestled over how to measure oil leaking from a runaway well a mile under the ocean. A senior scientist who led the federal effort, Bill Lehr of the National Oceanic and Atmospheric Administration, noted that the administration went public with a summary of estimates before experts could finish their work.


"It's easy to second guess in hindsight the wisdom of presenting the five-page summary ... while we were still refining and improving its estimates," he wrote. "I personally wish that the report had included the uncertainty that we know exists and is built into the calculator." Lehr said the work represented "our best guess," adding: "Yes, it is a guess."


EPA Administrator Lisa Jackson was "concerned about the level of certainty implied in the pie and cylinder charts." Another e-mail noticed that a pie chart in a draft of the government's report wasn't actually round: "A pie chart pretty much has to round to 100," NOAA spokeswoman Jennifer Austin wrote.


Lehr's top boss at NOAA, Jane Lubchenco, cautioned a colleague about how to present the government's findings: "I believe we owe it to everyone to provide the best estimates we can where direct measurements are not possible," she wrote. "We also need to be forthright about how certain we are about each number, which we've done."


The e-mails were obtained by The Associated Press under the Freedom of Information Act.


U.S. officials clearly understood the possible economic consequences of their findings. Anticipating a question in August for an upcoming news conference, a NOAA spokeswoman asked scientists, "What impact, if any, will this report have in determining BP's financial liability for this spill?" The answer: The U.S. can fine BP up to $4,300 per barrel of oil that is counted as leaked.


The documents released Wednesday by the Commerce Department, NOAA's parent agency, were significant because they revealed conversations among scientists working on the forecasts of oil in the Gulf. The government released 5,817 pages of files late in the afternoon on the eve of Thanksgiving, traditionally a period when few people are paying attention to news reports because of holiday travel.