Texas Civil Practice and Remedies Code - CIV PRAC & REM § 15.065. Watercourse or Roadway Forming County Boundary

If a river, watercourse, highway, road, or street forms the boundary line between two counties, the courts of each county have concurrent jurisdiction over the parts of the watercourse or roadway that form the boundary of the county in the same manner as if the watercourse or roadway were in that county.