In order to insure the payment of the general obligation bonds of the town, the payment of which is additionally secured by a pledge of revenues of such improvements, of any such other income-producing project and of any such excise taxes, as provided in NRS 269.410, or other such additionally secured general obligation securities of the town, the board may establish and maintain, and from time to time revise, a schedule or schedules of fees, rates and charges for services, facilities and commodities rendered by or through such improvements and any such other income-producing project and a schedule or schedules of any such excise taxes, as the case may be, in an amount sufficient for that purpose and also sufficient to discharge any covenant in the proceedings authorizing the issuance of any of the bonds or other securities, including any covenant for the establishment of reasonable reserve funds.