Any such agreement with any landowner shall give the commission jurisdiction of such land, waters, and streams to accomplish the purposes set out in said agreement and in case any improvement contemplated by section 456B.7 is for the sole purpose of improving any stream and not mainly for the purpose of preventing silting in a state-owned lake, then said agreement with the landowner shall include an easement of public access to said stream where improved and along the banks thereof.
Iowa Code § 456B.8