The district is composed of the territory described by Section 1, Chapter 398, Acts of the 51st Legislature, Regular Session, 1949, as that territory may have been modified under:
(1) Subchapter O, Chapter 51, Water Code;
(2) Subchapter J, Chapter 49, Water Code;
(3) Subchapter E or the relevant parts of its predecessor statute, former Section 4A, Chapter 398, Acts of the 51st Legislature, Regular Session, 1949; or
(4) other law.