The boundaries of the district are coextensive with the boundaries of Gonzales County except the district does not include the territory of the following districts that lie within the county as those districts existed on January 1, 1975:
(1) Nixon Hospital District of Gonzales and Wilson Counties;
(2) DeWitt Medical District;
(3) Yoakum Hospital District; and
(4) Shiner Independent School District of Shiner and Lavaca Counties.