16 U.S. Code § 728 - Expenditures
The Secretary of the Interior is authorized to make such expenditures for construction, equipment, maintenance, repairs, and improvements, including expenditures for personal services at the seat of government and elsewhere, as may be necessary to execute the functions imposed upon him by this chapter and as may be provided for by Congress from time to time.
As originally enacted, this section contained an additional paragraph which appropriated a sum half of which was to be available, until expended, for the expenditures mentioned herein.
Transfer of functions of Secretary of Agriculture and Secretary of Commerce to Secretary of the Interior, by Reorg. Plan No. II of 1939, see Transfer of Functions note set out under section 723 of this title.