253.230.  Revenue bonds — conditions of issue, approval, sources of payment — department of natural resources building fund. — 1.  For the purpose of providing funds for the acquisition, construction, erection, equipment, and furnishing a project and providing a site therefor, as herein provided, the department of natural resources has the power to issue and sell to the extent of the appropriations made therefor revenue bonds in an amount not to exceed the estimated cost of the project including costs necessarily incidental thereto.

  2.  No revenue bonds shall be issued and sold unless, at the time of issuance, the department of natural resources shall first obtain the approval of the governor and general assembly and

  (1)  Pledge the net income and revenues of the project to the payment of the bonds, both principal and interest, and, in the discretion of the department of natural resources, any one or more of the following:

  (a)  The proceeds of any grant in aid of the project which may be received from any source;

  (b)  The net income and revenues arising from the operation of the park in which the project is located;

  (c)  The net income and revenues arising from the operation of one or more other projects, as herein defined, owned and operated by the department of natural resources; or

  (d)  The net income and revenues received from contracts entered into for the management of any state park or for the exercise of any concession, privilege, facility or convenience within any state park;

  (2)  Covenant to fix, maintain and collect such reasonable rates and charges for the use of the projects as in the judgment of the department will provide revenues sufficient to pay the reasonable cost of operating and maintaining the project;

  (3)  Provide and maintain an interest and sinking fund in an amount adequate promptly to pay the principal of and interest on the bonds;

  (4)  Provide a reasonable reserve fund;

  (5)  Provide a reasonable fund for depreciation.

  3.  The department of natural resources is authorized in its discretion to use any unencumbered available funds on hand received from the net income and revenues arising from the operation of any project, as herein defined, owned and operated by the department of natural resources, or received from contracts entered into for the management of any state park or for the exercise of any concession, privilege, facility or convenience within the state park, not to exceed fifty percent of the preceding fiscal year's deposits to the department of natural resources earnings fund, to pay the principal of or the interest on any revenue bonds issued by the department of natural resources for the purpose of providing funds for the acquisition, construction, erection, equipment and furnishing a project and providing a site therefor, or to establish any interest and sinking fund or reserve fund for the benefit of any such revenue bonds.

  4.  No revenue bonds shall be issued and sold if private facilities are adequate in the given park area.

  5.  The proceeds of the sale of any bonds issued hereunder shall be paid into the state treasury to the credit of a fund to be known as the "Department of Natural Resources Building Fund" which is hereby created.