Seven members of the California Water Commission appointed by the Governor shall be selected and approved for appointment on the basis of their general educational and business qualifications, and their knowledge of, interest in, and experience with problems relating to the control, storage, and beneficial use of water. They shall be appointed in such a manner as to afford representation on the commission of all parts of the state so far as it is practicable. In considering qualifications of such members of the commission, engineering ability and experience shall be deemed advisable. Two members of the commission appointed by the Governor shall be members of the public having an interest in and knowledge of the environment and need have none of the other qualifications specified in this section. The next two members appointed to the commission by the Governor after the effective date of the amendment of this section at the 1970 Regular Session of the Legislature shall be members of the public having such interest in and knowledge of the environment.