Tennessee Code Title 5. Counties § 5-6-120

(a)(1) The duties of the county mayor in regard to any petition filed pursuant to title 7, chapter 82, are transferred to the water and wastewater treatment authority board under title 68, chapter 221, part 6 in any county that has created such authority. The preceding sentence does not apply to any petition by any governmental entity or state instrumentality that does not purport to adjust or otherwise modify any territory included in the service area of a water and wastewater treatment authority. Such petitions may be granted if the board determines in its sole discretion that the public convenience and necessity require the same. The general assembly enacts this section as a statement of its intent that this section is a clarification of title 68, chapter 221, part 6. From and after the creation of a water and wastewater treatment authority and the establishment of its service area, the authority shall be the sole and exclusive provider of its authorized services in its service area. The designated service area for any particular function or service shall not include any area located within the boundaries of another governmental entity providing the same function or service on the date the service area is established. Different service areas may be established for different functions or services. The authority may cede all or any portion of its functions or service area to another governmental entity upon the board determining in its sole discretion that the public convenience and necessity require the same.

(2) Notwithstanding any law to the contrary, the transfer of duties as provided in subdivision (a)(1) do not apply to a county which: