The board of directors of any irrigation district issuing such revenue bonds shall provide for revenues by fixing rates and charges for furnishing the service involved as the board shall deem necessary, in the manner provided by law and as fixed by resolution, the total revenues to be so estimated and determined as to be sufficient to take care of costs of maintenance, operation interest and principal amortization requirements and other charges involved.
RCW 87.28.090
Assessments and levies: RCW 87.03.240 through 87.03.305.