Whenever any of the public lands are embraced within the boundaries of any city of this state, and the city authorities deem it necessary that a sewer system, street improvements or other public improvements of any kind, authorized by general law, be made therein for the preservation of the health, accommodation or convenience of such inhabitants, the city council may, by ordinance, provide for the assessment of a portion of the expense of such improvement against unpatented lots, blocks or parcels of land, and the improvements thereon, embraced within the limits of such city, to the same extent and amount as though such lands were patented. When patents issue for such lands the lien of the assessment against each lot, piece and parcel of land shall attach immediately and be enforced and collected as other taxes, or as provided, by ordinance, of such city; provided, this section shall not apply nor authorize the creation of any lien upon state lands.