This environmental assessment (EA) addresses one proposed Federal action: oil and gas Lease Sale 200 in the Western Planning Area (WPA) of the Gulf of Mexico (GOM) Outer Continental Shelf (OCS) as scheduled in the Outer Continental Shelf Oil and Gas Leasing Program 2002-2007 (5-Year Program) (USDOI, MMS, 2002a). This EA incorporates by reference all of the relevant material in the multisale environmental impact statement (EIS) from which it tiers (Gulf of Mexico OCS Oil and Gas Lease Sales: 2003-2007; Central Planning Area Sales 185, 190, 194, 198, and 201; Western Planning Area Sales 187, 192, 196, and 200; Final Environmental Impact Statement; Volumes I and II (USDOI, MMS, 2002b). Additionally, since new information was identified and analyzed in the Lease Sale 196 EA (USDOI, MMS, 2005a), this EA also incorporates by reference all of the relevant material in the Lease Sale 196 EA and the Lease Sale 192 EA (USDOI, MMS, 2004). The EA has been prepared to aid in the determination of whether or not new available information indicates that the proposed lease sale would result in new significant impacts not addressed in the multisale EIS.