571—40.35 (462A) Speed restrictions on the Greene Impoundment of the Shell Rock River. No motorboat shall be operated at a speed exceeding five miles per hour in the two zoned areas of the Greene Impoundment designated by buoys or other approved uniform waterway markers. The first zoned area extends from the dam in the city of Greene, upstream approximately one-quarter mile to the north boundary of the city park in which the lower boat ramp is located. The second zoned area extends from the county bridge over the Shell Rock River on the north side of section 28 of Union Township in Floyd County, downstream approximately one-quarter mile to the south boundary of Gates Bridge County Park. The city of Greene and Floyd County shall designate their respective speed zones with uniform waterway markers (buoys) approved by the natural resource commission.