Not later than October 1, 1979, the Department of Human Resources shall adopt rules which provide a statewide eligibility standard to certify residents of each county as indigent for the purposes of this article. These rules shall further provide that certification as indigent for the purposes of this article may occur either prior to a person's admission to a regional referral hospital, or subsequent to such admission for an emergency condition, but in any event if a determination of whether a patient meets or does not meet eligibility standards for certification as indigent for the purpose of this article is not made within 90 days following written notification by the regional referral hospital to the county of residence of the patient's admission to a regional referral hospital, the patient shall be considered to have been a certified indigent patient upon admission. A patient certified as indigent for the purpose of this article subsequent to his or her admission to a regional referral hospital shall be considered to have been certified upon admission. Such certification shall be made by a person designated by the board of county commissioners, or in the absence of such a designated person, by the county health officer. Furthermore, any county may establish standards of eligibility which are less restrictive than the standards adopted by the department under this section and no county may establish standards which are more restrictive than the standards adopted by the department under this section.