This document is an Environmental Assessment (EA) for an action to amend halibut Individual Fishing Quota (IFQ) and Community Development Quota (CDQ) regulations that define regulatory fishing areas for these programs under the authority of both the National Marine Fisheries Service (NMFS) and International Pacific Halibut Commission (IPHC). In December 2004, the North Pacific Fishery Management Council (Council) identified its preferred alternative to allow holders of Area 4C halibut IFQ and CDQ to harvest such halibut IFQ/CDQ in Area 4D. It would allow additional fishing opportunities so that the assigned Area 4C IFQ and CDQ quotas for two Pribilof Island ommunities (St. Paul and St. George) in Area 4C may be attained. A complementary action by the IPHC, which is required to adopt this regulatory amendment, was approved in January 2005.