The number of board members required to make a decision on a case differs depending on the type of case.

(1) Short-board appeals. Pursuant to RCW 43.21B.305, an appeal that involves a penalty of fifteen thousand dollars or less imposed by the department of ecology, another state agency or an air pollution control authority or that involves a derelict or abandoned vessel under RCW 79.100.120 may be heard by a single member of the board. Such appeals are called short-board appeals. The decision of that single member shall be the final decision of the entire board. For appeals that involve a derelict or abandoned vessel under RCW 79.100.120 only, an administrative appeals judge employed by the board may be substituted for a board member.

(2) Full-board appeals. All other types of appeals are called full-board appeals. The chairperson may assign a single member to hold the hearing in a full-board appeal; however, at least two members shall review the record and issue a decision. Two members of the board shall constitute a quorum for making a decision and may act although one position on the board is vacant or one board member is unavailable.

(3) Administrative appeals judges. For both full-board and short-board cases, the chairperson may appoint an administrative appeals judge from the environmental and land use hearings office to be the presiding officer.