This chapter applies only to:
(1) a county that:
(A) contains a municipality that has a population of 500,000 or more;
(B) is located on the international border; and
(C) before September 1, 2009, had a county ethics board appointed by the commissioners court;
(2) a county that:
(A) has a population of 425,000 or more;
(B) is adjacent to a county with a population of 3.3 million or more; and
(C) contains a portion of the San Jacinto River; and
(3) a county that has a population of less than 50,000 that is adjacent to a county with a population of more than 3.3 million.