Apparently, the lease grant to BP was exempted from environmental review, according to the Washington Post’s Juliet Eilperin:
The decision by the (Interior) department’s Minerals Management Service (MMS) to give BP’s lease at Deepwater Horizon a “categorical exclusion” from the National Environmental Policy Act (NEPA) on April 6, 2009 — and BP’s lobbying efforts just 11 days before the explosion to expand those exemptions — show that neither federal regulators nor the company anticipated an accident of the scale of the one unfolding in the gulf.
The reason was the allegedly minimal risk of harm from an oil spill:
In one assessment, the agency estimated that “a large oil spill” from a platform would not exceed a total of 1,500 barrels and that a “deepwater spill,” occurring “offshore of the inner Continental shelf,” would not reach the coast. In another assessment, it defined the most likely large spill as totaling 4,600 barrels and forecast that it would largely dissipate within 10 days and would be unlikely to make landfall.
This is actually all-too-typical of the lousy job that agencies do at risk analysis in conducting environmental reviews, as I have discussed elsewhere. Here are some prescriptions for fixing this problem.