64.231.  Master plan, contents, amendment, hearings, adoption, recording. — 1.  The county planning board shall have power to make, adopt and may publish an official master plan for the county for the purpose of bringing about coordinated physical development in accordance with present and future needs.  The master plan shall be developed so as to conserve the natural resources of the county, to ensure efficient expenditure of public funds, and to promote the health, safety, convenience, prosperity and general welfare of the inhabitants.  The master plan may include, among other things, a land use plan, studies and recommendations relative to the locations, character and extent of highways, railroads, bus, streetcar and other transportation routes, bridges, public buildings, schools, sewers, parks and recreation facilities, parkways, forests, wildlife refuges, dams and projects affecting conservation of natural resources.  The county planning board may adopt the master plan in whole or in part, and subsequently amend or extend the adopted plan or any portion thereof.  Before the adoption, amendment or extension of the plan or portion thereof, the board shall hold at least one public hearing thereon, fifteen days' notice of the time and place of which shall be published in at least one newspaper having general circulation within the county, and notice of the hearing shall also be posted on the county's website.  The hearing may be adjourned from time to time.  The adoption of the plan shall be by resolution carried by not less than a majority vote of the full membership of the county planning board.  After the adoption of the master plan an attested copy shall be certified to the county clerk and a copy shall be recorded in the office of the recorder of deeds.

  2.  The master plan, with the accompanying maps, diagrams, charts, descriptive matter, and reports, shall include the plans specified by this section which are appropriate to the county and which may be made the basis for its physical development.  The master plan may comprise any, all, or any combination of the plans specified in this section, for all or any part of the county.