(a) Notwithstanding any provision of law other than section 401(b) of the Natural Gas Policy Act of 1978, or any other rule, regulation, or order of the Department of Energy, the Federal Energy Regulatory Commission or their predecessor agencies, and to the maximum extent practicable, no curtailment plan of an interstate pipeline may provide for curtailment of deliveries of natural gas for any essential agricultural use, unless:

(1) Such curtailment does not reduce the quantity of natural gas delivered for such use below the use requirement certified by the Secretary of Agriculture under section 401(c) of the Natural Gas Policy Act of 1978 in order to meet the requirements of full food and fiber production; or

(2) Such curtailment is necessary in order to meet the requirements of high-priority users; or

(3) The Federal Energy Regulatory Commission, in consultation with the Secretary of Agriculture, determines, by rule or order issued pursuant to section 401(b) of the Natural Gas Policy Act of 1978, that use of a fuel (other than natural gas) is economically practicable and that the fuel is reasonably available as an alternative for such essential agricultural use.

(b) Any essential agricultural user who also qualifies as a high-priority user shall be a high-priority user for purposes of paragraph (a) of this section.

(c) The specific relative order of priority for all uses and users of natural gas, including high-priority and essential agricultural uses and users, shall remain as reflected in effective curtailment plans of interstate pipelines filed with the Federal Energy Regulatory Commission to the extent that the relative order of priorities does not conflict with paragraph (a) of this section.

(d) Nothing in this rule shall prohibit the injection of natural gas into storage by interstate pipelines or deliveries to its customers for their injection into storage unless it is demonstrated to the Federal Energy Regulatory Commission that these injections or deliveries are not reasonably necessary to meet the requirements of high-priority users or essential agricultural uses.