Chapter 18A.70 PCC applies to lots, structures, and uses which were legally established prior to the adoption, revision, or amendment of Title 18A PCC, and which remain legal, but have become nonconforming as a result of this Title's application. If the County has a Joint Planning Agreement with a city or town for management of land use within the city or town's urban growth area, and the Agreement specifically identifies the use of alternative nonconforming standards within that area, then those standards shall apply.