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, and also any amounts pursuant to contracts or leases referred to in this part applicable to the Marin Municipal Water District, the board shall cause a tax to be levied, 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.