Iowa Code § 309.63: Gravel beds.

The board of supervisors of any county may, within the limits of such county and outside the limits of any city, purchase or condemn any lands for the purpose of obtaining gravel or other suitable material with which to improve the secondary roads of such county, including a sufficient roadway to such land by the most reasonable route, or the board may purchase such material outside the limits of their county. In either case, the board may pay for the materials out of the secondary road funds.