 However, the river was in a high flood stage during the six month rainy season, during this time Yaxchilan became an island due to the swiftly flowing waters of the engorged river which encompassed the city.An all-weather passage across the treacherous river was a necessity in order to gain access to the farmlands to the north of the city.To survive and operate efficiently as the seat of power, Yaxchilan required a dependable passageway to provide an uninterrupted flow of traffic across the river on a year-round basis.