Notwithstanding any existing law to the contrary, the county auditor of any county, is hereby authorized on behalf of the state, for such price and on such terms and conditions, including provision for reversion in the event of nonuser, as the county board may prescribe, to convey to the United States or to the state of Minnesota upon tax-forfeited lands under the administration of the county, permanent or temporary easements for specified periods or otherwise for highways, roads and trails, flowage for development of fish and game resources, stream protection, flood control, and necessary appurtenances thereto.