Sec. 4. Only the provisions of this Act and of Articles 1672 and 1673 shall apply in counties having a population of not less than seventy-five thousand (75,000), and not more than eighty thousand (80,000), according to the last preceding Federal Census, which contain Navigation Districts, Water Improvement Districts, and Water Control and Improvement Districts.
Sec. 5. If any provision of this Act is held to be unconstitutional or otherwise invalid, same shall not affect the validity of any other provision hereof.