The Secretary of the Smithsonian Institution shall fix the annual rates of basic pay for positions on the police force of the National Zoological Park as follows:

(1) Private, not more than the maximum annual rate of basic pay payable for grade GS-7 of the General Schedule.

(2) Sergeant, not more than the maximum annual rate of basic pay payable for grade GS-8 of the General Schedule.

(3) Lieutenant, not more than the maximum annual rate of basic pay payable for grade GS-9 of the General Schedule.

(4) Captain, not more than the maximum annual rate of basic pay payable for grade GS-10 of the General Schedule.