The defenses of waiver, abandonment, and "changed conditions" are set out in the Texas Supreme Court's decision in Cowling v. Colligan, 158 Tex. 458, 312 S.W.2d 943 (1958). In that case, the court identified two separate defenses to the enforcement of deed restrictions, as follows: (1) where lot owners have acquiesced in "such substantial violations within the restricted area as to amount to an abandonment of the covenant or a waiver of the right to enforce it"; (2) where "there has been such a change of conditions in the restricted area or [area] surrounding it that it is no longer possible to secure in a substantial degree the benefits sought to be realized through the covenant." Cowling, 312 S.W.2d at 945. Thus, the defense of "changed conditions" is distinct from the defense of "waiver and abandonment" as it relates to the enforcement of deed restrictions. See Traeger v. Lorenz, 749 S.W.2d 249, 250-51 (Tex. App.--San Antonio 1988, no writ).