The general assembly hereby declares that it is necessary for sound and healthful urban and metropolitan development, and in the public interest, for the state or any county having a population in excess of two hundred thousand, or any county adjoining, or city not within but adjoining such county, to expend or advance public funds for, or to accept, any interest in land herein described for the purpose of acquiring, maintaining, improving, protecting, limiting the future use of, or otherwise conserving and properly utilizing open spaces and areas within such counties, or cities, and the acquisition of such interests in land shall be deemed for a public purpose.