All persons who have enjoyed the use of the water in any natural stream for the irrigation of any meadow land by the natural overflow or operation of the water of such stream, in case the diminishing of the water supplied by such stream, from any cause, prevents such irrigation therefrom in as ample a manner as formerly, shall have right to construct a ditch for the irrigation of such meadow and to take water from such stream therefor. Their right to water through such ditch shall have the same priority as though such ditch had been constructed at the time they first occupied and used such land as meadow ground.