Michigan Compiled Laws, Chapter 254. Bridges § 254.60

Sec. 10. Whenever in any county in which the county road system, so-called, shall not have been adopted, the board of supervisors shall, pursuant to sections 1 and 2 hereof,  1 have ordered a bridge to be constructed or reconstructed, full authority of every necessary character shall thereupon be vested in said board to construct or reconstruct as the case may be, such bridge. In furtherance thereof, said board may delegate any of its powers and duties to any of its officers, or to its committee or committees, or to any or all of them as it may deem suitable.