The department shall examine all information concerning the person for whom admission is requested and shall determine therefrom whether the person is a person with an intellectual disability and whether residence in the residential facility is necessary for the welfare, care, treatment, or training of such person. Such determination shall be made in writing and shall set forth the reasons for the determination. If at any time it shall become necessary, for want of room or other cause, to discriminate in the admission of persons with an intellectual disability to residential facilities, the selection shall be made as follows: (1) Persons whose care is necessary in order to protect themselves or the public health and safety; (2) persons who are most likely to be benefited thereby; (3) persons shall next be admitted in the order in which their applications for admission have been filed with the department; and (4) when cases are equally meritorious in all other respects, an indigent person or a person from an indigent family shall be given preference.