Utah Code § 17-79-701: Enactment of subdivision ordinance.

(1) The legislative body of a county may enact ordinances requiring that a subdivision plat comply with the provisions of the county's ordinances and this part before:

(a) the subdivision plat may be filed and recorded in the county recorder's office; and

(b) lots may be sold.

(2) If the legislative body fails to enact a subdivision ordinance, the county may regulate subdivisions only as provided in this part.

(3) The joining of a lot or lots to a parcel does not constitute a subdivision as to the parcel or subject the parcel to the county's subdivision ordinance.

(4) A legislative body may adopt a land use regulation that specifies that combining lots does not require a subdivision plat amendment.