It is the intent of the legislature wherever possible to place the internal affairs of the department under the control of the secretary to institute the flexible, alert and intelligent management of its business that changing contemporary circumstances require. Therefore, whenever the secretary's authority is not specifically limited by law, he or she shall have complete charge and supervisory powers over the department. The secretary is authorized to create such administrative structures as deemed appropriate, except as otherwise specified by law. The secretary shall have the power to employ such assistants and personnel as may be necessary for the general administration of the department. Except as elsewhere specified, such employment shall be in accordance with the rules of the state civil service law, chapter 41.06 RCW.