Draft if sea: sea was removed restore sea, set owner to water (set canal not on river) if bare land: self canal was removed restore canal, set canal to self set canal not on river if river && canal on river: self canal was removed restore canal, set canal to self set canal on river if river && canal not on river: (it's a real river) maintain river, maintain owner (maintain canal not on river) if canal && canal not on river: (it's not our canal) maintain canal, set canal to its owner (maintain canal not on river) if canal && canal on river: (it's not our canal) maintain canal, set canal to its owner (maintain canal on river)