All improvements within said park and upon any additions thereto shall be made under the direction of the park and recreation board of the department of parks and recreation and all costs of such improvements, together with the expense of maintaining and governing said park shall be paid out of the appropriation made to the board for that purpose and all revenue derived from said park shall be paid into the park and recreation fund of the state of Idaho. The expense of acquiring and improvement of real estate adjacent to the said park, which is necessary to the complete enjoyment, sanitation, improvement and protection of the park, by purchase, condemnation or otherwise, shall be deemed to be incidental to the operation, administration or improvement of the said park.