§ 359. Rates and fees. A company shall, with the approval of the commissioner, fix maximum rates and fees to be charged persons served by each project for the facilities and services provided by the company to such persons, the average of such rates and fees for any one project not to exceed the maximum average rates and fees determined by the commissioner before any commitments are made by the company for the construction, acquisition, reconstruction, rehabilitation or improvement of the project. The commissioner upon his own motion, or upon application by the company or lienholder may vary the amount of such rates and fees from time to time so as to secure together with all other income of the company, sufficient income to meet, within reasonable limits, all necessary payments by the said company of all expenses, including fixed charges, sinking funds and reserves.