Whenever the board of supervisors of any county shall have adopted a resolution to purchase, condemn or to accept certain lands for park purposes, and make an appropriation therefor under the provisions of section 1 and 2 of this act, there shall be created a board of 3 members to be known and designated as “county park trustees.” In counties operating under the county road system, the board of county road commissioners is hereby designated and shall then act as the county park trustees. In all other counties the board of supervisors, at the time of making the appropriation above provided for, shall name and appoint from their number 3 members to be known and designated as county park trustees. Said board of trustees shall have the management, control and expenditure of such funds when collected and shall hold in trust for the county the title to any real estate so purchased, acquired by condemnation or accepted by way of gift or devise for park purposes, and shall supervise the improvement of any such property so purchased, acquired or accepted as authorized by the board of supervisors. Said board of park trustees shall have the power to impound water on any property so purchased, acquired by condemnation or accepted for park purposes and to form a lake thereon whenever they deem it necessary in the course of improving such property for park purposes. Such trustees shall also have the care and control of such park property and may make reasonable rules and regulations and enforce the same when made respecting the use by the public of such park property: Provided, That no such rule or regulation shall become effective until (1) it has been approved by resolution of the board of supervisors, (2) such resolution containing such rule or regulation has been published at least once in a newspaper of general circulation within the county, and (3) such rule or regulation has been posted in at least 3 conspicuous places in such park property, the posters to be not less than 10 inches by 12 inches in size and printed in legible type. Such posting shall be continuously maintained. They shall elect a chairman and secretary from among their number. All expenditures of funds so appropriated shall be paid only by the county treasurer on the warrant or voucher of the chairman and 1 other member of such board. The trustee so appointed shall make a full report to the board of supervisors at each October session as to the condition of the property and the expenditure of funds. The members of such board of county park trustees shall continue to act until their successors have been duly elected or appointed. In all counties of this state operating under the county road system when this act takes effect, the board of “county park trustees” heretofore appointed shall be immediately dissolved and cease to exist, and the board of county road commissioners shall take the place thereof and thereafter exercise the powers and perform the duties of the board of county park trustees, taking possession of all books, records and office equipment of such former board.