Texas Local Government Code - LOC GOV'T § 241.019. Nonconforming Uses and Structures

(1) changes in nonconforming land use existing on the date of the adoption of the regulations;

(2) the removal, lowering, or other change of a structure that does not conform to the regulations on the date of their adoption, including all phases or elements of a multiphase structure, regardless of whether actual construction has commenced, that received a determination of no hazard by the Federal Aviation Administration under 14 C.F.R., Part 77, before the regulations were adopted;

(3) the removal, lowering, or other change of an object of natural growth that does not conform to the regulations on the date of their adoption; or

(4) any other interference in the continuation of a use that does not conform to the regulations on the date of their adoption.