Ala. Code § 11-50-530: Rates and Charges for Services Rendered.

The rates and charges for the services rendered by or from any utility owned or operated by the corporation shall at all times be reasonable for the services so rendered and as low as consistent with good service and prudent management, but shall be sufficient to pay all expenses necessary for the operation of its properties and the maintenance thereof in good operating condition, the payment of the principal of and interest on all bonds issued by it and the creation and maintenance of such reserves for improvements, new construction, depreciation, and contingencies as the board may from time to time prescribe in the exercise of sound judgment and prudent management. In the event the revenues of the corporation shall be in excess of those necessary for said purposes, the corporation shall reduce its said rates and charges as the board may prescribe. All schedules of such rates and charges shall be uniform throughout the power district.