The board of directors of any irrigation district which shall have entered into a contract or contracts with the United States may, by passing a resolution to that effect and the publication thereof for at least two (2) weeks in a newspaper published in the county in which the greater portion of the lands of the district are located, provide for the levy and collection of assessments for operation and maintenance purposes as hereinafter provided and so fix the dates of such levy, assessment and delinquency that such separate operation and maintenance charge and the assessment therefor will become delinquent on the first day of March next following such levy and assessment.