If in such referendum called under the provisions of this Article two thirds or more of the voters eligible and voting vote in the affirmative and in favor of the levying and collection of such assessment proposed in such referendum, then such assessment shall be collected annually, or more often as predetermined by the agency, for the three years set forth in the call for such referendum, and the collection of such assessment shall be under such method, rules, and regulations as may be determined by the agency prior to the announcement of the referendum and included in the announcement of the referendum; said assessment so collected shall be paid into the treasury of the agency, to be used together with other funds, including donations and grants from individuals, firms, governmental agencies, or corporations, and from other fees, dues, or assessments,  for the purpose set out in the referendum. (1967, c. 890, s. 12.)