In addition to the annual charges or assessments provided for in ORS § 548.315, and in addition to the charges or assessments authorized by law for the maintenance and operation of drainage and irrigation districts, such contract may provide that the board shall impose an annual charge not to exceed 50 cents per acre upon each acre in the district. All moneys received from the charge shall be placed by the treasurer of the district in a fund to be designated as the ’emergency fund.’ The emergency fund shall be used for supplementing the bond fund in case of deficiency due to accident, delinquency or other contingencies. The fund shall be disbursed by the treasurer upon the order of the board. [Amended by 1989 c.182 § 32; 1991 c.459 § 426a; 1997 c.170 § 54]