Mich. Comp. Laws § 280.322
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 road commission having jurisdiction, or by the state highway commissioner if such highway is a state trunk line. 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. The board of county road commissioners or the state highway commissioner shall assume and bear such portion of the cost of construction, based upon benefits, as may be agreed upon with the drain commissioner. In such case, 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. Thereafter such bridge or culvert constructed under the provisions of this act shall be maintained by the county road commission or state highway commissioner. Any such expense charged to the state highway commissioner shall be met out of any funds appropriated for the state highway department that may be available therefor; and any such expense to be borne by the board of county road commissioners shall be paid out of moneys in the county road fund not otherwise appropriated. As part of such drain, there shall be constructed at least 1 bridge or culvert across such drain connecting the highway (except limited access highways established under Act No. 205 of the Public Acts of 1941, as amended, being sections 252.51 to 252.64 of the Compiled Laws of 1948), with each farm entrance, and when a drain crosses a farm or any portion thereof there shall be constructed 1 bridge, culvert or ford across the drain connecting the portions of the farm disconnected by the drain, which bridge, culvert or ford shall also be charged in the first instance as a part of the construction of such drain, after which such bridge, culvert or ford shall be maintained by the owner of the land. If the drain commissioner shall make future improvements such as widening, deepening, straightening or relocating such drain, but not clean out alone, there shall be constructed the necessary bridges, culverts and fords as parts of such improvements.
MCL 280.322