Each commissioner shall receive ninety dollars for each day or portion thereof spent in actual attendance at official meetings of the district commission, or in performance of other official services or duties on behalf of the district, to include meetings of the commission of his or her own district, or meetings attended by one or more commissioners of two or more districts called to consider business common to them, except that the total compensation paid to such commissioner during any one year shall not exceed eight thousand six hundred forty dollars. The commissioners may not be compensated for services performed of a ministerial or professional nature.

Any commissioner may waive all or any portion of his or her compensation payable under this section as to any month or months during his or her term of office, by a written waiver filed with the district as provided in this section. The waiver, to be effective, must be filed any time after the commissioner's election and prior to the date on which the compensation would otherwise be paid. The waiver shall specify the month or period of months for which it is made.

Any district providing group insurance for its employees, covering them, their immediate family, and dependents, may provide insurance for its commissioners with the same coverage. Each commissioner shall be reimbursed for reasonable expenses actually incurred in connection with such business and meetings, including his or her subsistence and lodging and travel while away from his or her place of residence. No resolution shall be adopted without a majority vote of the whole commission. The commission shall organize by election of its own members of a president and secretary, shall by resolution adopt rules governing the transaction of its business and shall adopt an official seal. All proceedings of the commission shall be by motion or resolution recorded in a book or books kept for such purpose, which shall be public records.

The dollar thresholds established in this section must be adjusted for inflation by the office of financial management every five years, beginning January 1, 2024, based upon changes in the consumer price index during that time period. "Consumer price index" means, for any calendar year, that year's annual average consumer price index, for Washington state, for wage earners and clerical workers, all items, compiled by the bureau of labor and statistics, United States department of labor. If the bureau of labor and statistics develops more than one consumer price index for areas within the state, the index covering the greatest number of people, covering areas exclusively within the boundaries of the state, and including all items shall be used for the adjustments for inflation in this section. The office of financial management must calculate the new dollar threshold and transmit it to the office of the code reviser for publication in the Washington State Register at least one month before the new dollar threshold is to take effect.

A person holding office as commissioner for two or more special purpose districts shall receive only that per diem compensation authorized for one of his or her commissioner positions as compensation for attending an official meeting or conducting official services or duties while representing more than one of his or her districts. However, such commissioner may receive additional per diem compensation if approved by resolution of all boards of the affected commissions.