Ala. Code § 9-9-46
Where any public ditch, drain or watercourse established under the provisions of this article crosses a public highway at the intersection of such highway with a natural watercourse or swale through which water flows during a period of high water, the cost of bridges or of repairing or enlarging existing bridges and culverts or of constructing new ones shall be borne by the county in which such bridges are located or by such other authority as is required by law to maintain such highway so intersected, and such bridges or culverts shall thereafter be maintained by such county or other authorities. Where any public ditch, drain or watercourse established under the provisions of this article crosses a public highway at a point where such highway does not intersect a natural watercourse or swale, the cost of constructing the new bridge required shall be borne by the water management district, and such bridge or culvert shall thereafter be maintained by and at the expense of the county or such other authority required by law to maintain such highway so intersected.
Ala. Code § 9-9-46 (1975)