22 U.S.C. § 277d–31

To defray costs that accrue to the United States under the agreement or agreements referred to in section 277d–30 of this title for the construction, operation, and maintenance of drainage conveyance canal projects, there are authorized to be appropriated to the Department of State for use of the United States Section, International Boundary and Water Commission, United States and Mexico, the following amounts: (1) Not to exceed $690,000 for costs of construction. (2) Upon completion of construction, not to exceed $25,000 based on estimated calendar year 1976 costs, plus or minus such amounts as may be justified by reason of ordinary fluctuations in operation and maintenance costs involved therein, annually for costs of operation and maintenance.