It is declared to be a legitimate county or municipal purpose for any county or incorporated city or town in the state to improve and beautify waterways, including lakes, rivers, streams, ditches and canals, within such county or municipality, by opening such waterways and by clearing them of logs and other obstructions, including water hyacinths and other disagreeable and obnoxious vegetation, and, for all or any part of such purpose, any county or incorporated city or town in the state may levy a tax not to exceed 1 mill on the dollar of the assessed valuation of all property assessed for taxes in such county or incorporated city or town.