Mich. Comp. Laws § 235.2
When any drain crosses a highway, the necessary bridge or culvert shall be constructed on the center line of the highway as located by survey, and in accordance with plans and specifications which shall be approved by the county, township or district highway commissioner having jurisdiction, or by the state highway commissioner if such road is a trunk line road, and such bridge or culvert shall be of a permanent nature and of sufficient strength to safely carry a 15 ton moving load. The cost of constructing the necessary bridge or culvert shall be charged in the first instance as part of the cost of construction of such drain after which such bridge or culvert shall be maintained as a part of the highway: Provided, however, That if such highway is a trunk line road, or is a county road, the state highway commissioner, or the board of county road commissioners, as the case may be, may assume and bear such proportion of the cost as may be agreed on between the drain commissioner and state highway commissioner or board. In such case however the contract for the construction of the bridge shall not be let by the drain commissioner without the written consent of the state highway commissioner or the board of county road commissioners. Any such expense assumed by the state shall be met out of any funds appropriated for the state highway department that may be available therefor; and the proportion of the cost of any bridge to be borne by the board of county road commissioners shall be paid out of moneys in the county road fund not otherwise appropriated. When a drain passes along a highway, there shall be constructed at least 1 bridge or passageway across such drain connecting the highway with each enclosed field and with each farm entrance, which bridge or passageway shall also be charged in the first instance as a part of the construction of such drain, after which such bridge or passageway shall be maintained by the owner of the land.
MCL 235.2