Districts may be established to build levees, straighten channels, and provide drainage. Legislative authorization for the establishment of levee-improvement districts was first given in the early 1900s, but several other relevant laws, including a 1918 law authorizing them to be established in conservation and reclamation districts already established, were later enacted. An application for the district must be signed by owners of more than 50 percent of the land value or at least fifty persons in proposed districts that hold more than fifty landholding residents and sent to the county commissioners' court or courts for the concerned county. Authorization is then subject to the approval of the state reclamation engineer. The districts are governed by a board of three supervisors, appointed by the county commissioners' court; the board appoints a district engineer to supervise construction and consult with the state reclamation engineer. The directors have the right to enter land to examine levees, drainage ditches, and other structures and may acquire right-of-ways for construction. Improvements may be paid for through contributions, assessments, taxes, and bonds. Many districts are on the Trinity River, beginning in Dallas County and extending downstream. Other districts are found on the West Fork of the Trinity and on the Sulphur and Brazos rivers. In 1992 forty-eight levee-improvement districts were registered with the Texas Water Commission.