; or (ii) a State management plan for reef-associated species. (D) Idle structure The term idle structure means— (i) an oil or gas pipeline, and associated equipment and infrastructure, that the Secretary of the Interior has determined is no longer useful for operations; and (ii) an offshore oil and gas platform or similar structure, and associated equipment and infrastructure, that is no longer useful for operations, as determined by the Secretary of the Interior. (E) Partial removal The term partial removal means— (i) the severance of the top portion of a structure at a level appropriate to maintain navigational safety, as determined by the Secretary of the Interior in consultation with the Commandant of the Coast Guard; and (ii) optionally, the placement of the severed portion of the structure on the sea floor adjacent to the base of the nonsevered portion of the structure. (F) Program The term Program means the artificial reef program authorized under the National Fishing Enhancement Act of 1984 ( 33 U.S.C. 2101 et seq. ). (G) Reef in place The term reef in place means decommissioning through topple in place or partial removal that— (i) attempts to maximize habitat for benthic and pelagic species throughout the entirety of the water column