This Environmental Assessment (EA) addresses the potential effects of oil and gas exploration, development, and production operations in the deepwater areas of the Gulf of Mexico Outer Continental Shelf (OCS) during the 10-year period 1998-2007. The western and central portions ofthe northern Gulf of Mexico constitute one of the world's major oil and gas producing areas, and have proved a steady and reliable source of crude oil and natural gas for more than 50 years