Government Code §74.091

(a) There is a local administrative district judge in each county. (b) In a county with two or more district courts the judges of those courts shall elect a district judge as local administrative district judge for a term of not more than two years. The local administrative district judge may not be elected on the basis of rotation or seniority. (c) In a county with only one district judge, the district judge serves as the local administrative district judge.