16 U.S.C. §§ 33–36

Any person, corporation, or company holding a lease within Yellowstone Park for the purposes described in section 32 of this title is authorized, with the approval of the Secretary of the Interior, to execute mortgages upon his or its rights, properties, and franchises, including his or its contract or contracts with the Secretary of the Interior, and such mortgages, together with the approval of the Secretary of the Interior may be filed for record in the office of the Secretary of the Interior, and when so recorded shall have all the effect of a public record. Any mortgage, lien, or encumbrance created under the provisions of this section shall be subject to the rights of the Government to compel the enforcement of the terms of the lease or contract of the mortgagor, and any purchaser under a foreclosure of such encumbrance shall take subject to all the conditions assumed by the original lessee or contractor.

Road extensions and improvements shall be made in the Yellowstone National Park under and in harmony with the general plan of roads and improvements to be approved by the Secretary of the Interior.

Private parties or companies doing business in the Yellowstone National Park under authority from the Government may be permitted, in the discretion of the Secretary of the Army, to use electricity furnished by the electric lighting and power plant of Fort Yellowstone and Mammoth Hot Springs at actual cost to the Government for operation, maintenance, and depreciation of the plant and 10 per centum additional, under such regulations as may be prescribed by the Secretary of the Army.

The Secretary of the Interior is authorized, in his discretion and under regulations to be prescribed by him, to give surplus elk, buffalo, bear, beaver, and predatory animals inhabiting Yellowstone National Park to Federal, State, county, and municipal authorities for preserves, zoos, zoological gardens, and parks. He may sell or otherwise dispose of the surplus buffalo of the Yellowstone National Park herd, and all moneys received from the sale of any such surplus buffalo shall be deposited in the Treasury of the United States as miscellaneous receipts.