For the purpose of creating a fund as prescribed in Section 42.1, a forest preserve district by resolution of its board may incur an indebtedness and issue bonds therefor, not to exceed in the aggregate $3,000,000 including the amount of all such bonds issued for this purpose prior to the effective date of this Act. Such bonds shall bear interest at not more than the maximum rate provided by law and shall mature within 20 years from the date thereof. The board may provide that the resolution or resolutions authorizing the issue of such bonds shall be operative, effective and valid without the submission thereof to the voters of such district for approval. The board of such district shall before or at the time of issuing such bonds provide for the collection of a direct annual tax upon all the taxable property in such district, sufficient to pay and discharge the principal thereof at maturity and to pay the interest thereon as it falls due.