70 ILCS 1205/9.1-4
Whenever revenue bonds are issued under Section 9.1-1 of this Article, all revenue derived from the operation of the golf course, or courses, shall be deposited in a separate fund designated as the "Golf Course Fund" of the park district. This fund shall be used only in paying the cost of operation and maintenance of the golf course, or courses, in providing an adequate depreciation fund, and in paying the principal of and interest upon the revenue bonds of the district issued under Section 9.1--1 of this Article.
A depreciation fund is a fund for such replacements as may be necessary from time to time for the continued effective and efficient operation of the golf course, or courses. Such a fund shall not be allowed to accumulate beyond a reasonable amount necessary for the purpose and shall not be used for extensions to the golf course, or courses.
70 ILCS 1205/9.1-4