In recognition of mounting public demands for recreational opportunities on areas within the National Wildlife Refuge System, national fish hatcheries, and other conservation areas administered by the Secretary of the Interior for fish and wildlife purposes; and in recognition also of the resulting imperative need, if such recreational opportunities are provided, to assure that any present or future recreational use will be compatible with, and will not prevent accomplishment of, the primary purposes for which the said conservation areas were acquired or established, the Secretary of the Interior is authorized, as an appropriate incidental or secondary use, to administer such areas or parts thereof for public recreation when in his judgment public recreation can be an appropriate incidental or secondary use: Provided, That such public recreation use shall be permitted only to the extent that is practicable and not inconsistent with other previously authorized Federal operations or with the primary objectives for which each particular area is established: Provided further, That in order to insure accomplishment of such primary objectives, the Secretary, after consideration of all authorized uses, purposes, and other pertinent factors relating to individual areas, shall curtail public recreation use generally or certain types of public recreation use within individual areas or in portions thereof whenever he considers such action to be necessary: And provided further, That none of the aforesaid refuges, hatcheries, game ranges, and other conservation areas shall be used during any fiscal year for those forms of recreation that are not directly related to the primary purposes and functions of the individual areas until the Secretary shall have determined—

(a) that such recreational use will not interfere with the primary purposes for which the areas were established, and

(b) that funds are available for the development, operation, and maintenance of these permitted forms of recreation. This section shall not be construed to repeal or amend previous enactments relating to particular areas.