Whenever the water users take over the care, operation, and maintenance of a project, or a division of a project, the total accumulated net profits, as determined by the Secretary, derived from the operation of project power plants, leasing of project grazing and farm lands, and the sale or use of town sites shall be credited to the construction charge of the project, or a division thereof, and thereafter the net profits from such sources may be used by the water users to be credited annually, first, on account of project construction charge, second, on account of project operation and maintenance charge, and third, as the water users may direct. No distribution to individual water users shall be made out of any such profits before all obligations to the Government shall have been fully paid.