 It then descends from the hilltop and crosses Davis Slough, a small stream that marks the boundary between Island and Snohomish counties.SR 532 continues across the wetland and crosses the main arm of the Stillaguamish River on the Camano Gateway Bridge at the west end of Stanwood.The highway runs through Stanwood on the south side of the city, following the bank of the Stillaguamish River.