Local Government Code §87.043

(a) In a county with a population of less than 150,000, a temporary absence occurs in the office of county judge if: (1) the county judge is located outside the county for 30 consecutive full days as a direct result of: (A) being a reservist or a member of the national guard who was ordered to duty under the authority of federal law; (B) enlisting in the armed forces or the national guard as a volunteer; or (C) being inducted into the armed forces under federal draft laws; and (2) the commissioners court determines in writing that the absence prevents the county judge from satisfactorily discharging the duties of the office. (b) If a temporary absence exists in the office of county judge, before the 30th day after the date the absence begins, the absent county judge may appoint a resident of the county to fill the office until the next term of that office or until the temporary absence ends, whichever event occurs first. If the absent county judge does not appoint a resident of the county within the 30-day period, the commissioners court shall appoint a resident of the county to fill the office until the next term of that office or until the temporary absence ends, whichever event occurs first.