There are authorized to be appropriated to the Department of State for the use of the Commission, out of any money in the Treasury not otherwise appropriated, such sums as may be necessary to carry out the provisions of the Treaty of February 3, 1944, and other treaties and conventions between the United States of America and the United Mexican States, under which the United States Section operates, and to discharge the statutory functions and duties of the United States Section. Such sums shall be available for construction, operation and maintenance of stream gaging stations, and their equipment and sites therefor; personal services and rent in the District of Columbia and elsewhere; services, including those of attorneys and appraisers, in accordance with the provisions of section 3109 of title 5, at rates for individuals not in excess of the maximum daily rate for grade GS–15 of the General Schedule and the United States Commissioner is authorized, notwithstanding the provisions of any other Act, to employ as consultants by contract or otherwise without regard to chapter 51 and subchapter III of chapter 53 of title 5, and the civil-service laws and regulations, retired personnel of the Armed Forces of the United States, who shall not be required to revert to an active status; travel expense, including, in the discretion of the Commissioner, expenses of attendance at meetings of organizations concerned with the activities of the Commission which may be necessary for the efficient discharge of the responsibilities of the Commission; hire, with or without personal services, of work animals, and animal-drawn, and motor-propelled (including passenger) vehicles and aircraft and equipment; acquisition by donation, purchase, or condemnation, of real and personal property, including expenses of abstracts, certificates of title, and recording fees; purchase of ice and drinking water; inspection of equipment, supplies and materials by contract or otherwise; drilling and testing of foundations and dam sites, by contract if deemed necessary; payment for official telephone service in the field in case of official telephones installed in private houses when authorized under regulations established by the Commissioner; purchase of firearms and ammunition for guard purposes; official entertainment and other representation expenses within the United States for the United States section; and such other objects and purposes as may be permitted by laws applicable, in whole or in part, to the United States Section: Provided, That, when appropriations have been made for the commencement or continuation of construction or operation and maintenance of any such project, the United States Commissioner, notwithstanding the provisions of sections 1341, 1342, and 1349 to 1351 and subchapter II of chapter 15 of title 31, and sections 6301(a) and (b) and 6303 of title 41, or any other law, may enter into contracts beyond the amount actually appropriated for so much of the work on any such authorized project as the physical and orderly sequence of construction makes necessary, such contracts to be subject to and dependent upon future appropriations by Congress: Provided further, That the United States Commissioner shall prepare, within 30 days after the end of each fiscal year, a report of all expenditures during that year for official entertainment and other representation expenses, which shall be available for public inspection.