Federal regulators exempted BP’s Gulf of Mexico drilling operation from a full environmental impact analysis last year after concluding that a massive oil spill was unlikely, The Washington Post reports. In three environmental assessments of drilling in the Gulf in 2007, the federal Minerals Management Service vastly underestimated the size and scope of a potential spill like the one that started two weeks ago when a deepwater rig leased by BP exploded and sank.

BP’s lease on the leaking rig was granted a waiver excluding it from the National Environmental Policy Act. The company has lobbied the government to provide these waivers more often. From The Post:

BP spokesman Toby Odone said the company’s appeal for NEPA waivers in the past “was based on the spill and incident-response history in the Gulf of Mexico.” Once the various investigations of the new spill have been completed, he added, “the causes of this incident can be applied to determine any changes in the regulatory regime that are required to protect the environment.”

An estimated 5,000 barrels of oil per day are leaking into the Gulf from the Deepwater Horizon platform.

Related: After Minimizing Danger of Oil Spill, BP Under Pressure to Stop Leak