Ohio Rev. Code Ann. § 755.28

The board of park trustees shall have the entire management and control of all work of straightening, cleaning, deepening, or otherwise improving any natural watercourse, whether partly or wholly used for sewer purposes or not, within the city, may purchase, acquire, or condemn any water rights, easements, or privileges in connection with any natural watercourse through such city, and may acquire or condemn such real estate as is necessary for such purposes.