If the revenues of the district, or of any improvement district therein, are or in the judgment of the board will probably be inadequate for any cause to pay the principal of or interest on any bonded debt of the district, or any improvement district thereof, as it becomes due and also the amounts set forth in Section 71616, the board shall cause a tax to be levied, as provided in this part, sufficient to provide for such deficit and to pay the amount of such principal and interest that will become due before the proceeds of a tax levied at the next general tax levy will be available.