Whenever the flood control project consists of a storage reservoir and authority to create, operate and maintain a reservoir on the river affected by such storage reservoir is vested in a duly organized river improvement company as defined by s. 182.016, and the petitioners file with the department of natural resources a petition and a proposed contract with such improvement company for a lease, sale, or lease with option to purchase said reservoir, and the department finds the terms and conditions of such contract are sufficient to assure the payment of the amount the board will be obligated to pay for the cost of the reservoir and the maintenance and operation of the same, and the project will secure effective flood control and promotion of the public welfare, then notices, proceedings and assessments provided by ss. 87.04 to 87.12 are not required. The department, however, shall make findings as required by s. 87.05 and shall order that the flood control board be appointed and shall so certify to the governor as provided by s. 87.12. The governor shall thereupon appoint the board as provided in said s. 87.12. The proposed contract filed with the department by petitioners for the sale, lease, or lease with option to purchase said reservoir property shall not be binding upon the board so appointed unless the board approves such contract. Upon approval the board shall so report to the department and file with it a final contract executed by the board and lessee or purchaser. The department has authority to approve or disapprove such contract. If the department approves such contract, then it shall be final and the department shall thereupon order the board to proceed with the work. When such reservoir property is sold and the purchase price has been fully paid and any indebtedness assumed by the purchaser has been paid and discharged, including the fees and expenses of the board, and the department so finds, the said board shall thereupon be dissolved by order of the department.