 WSDOT conducts an annual survey of average traffic volume on the state highway system that is measured in terms of average annual daily traffic.Traffic volumes on SR 530 range from a minimum of 1,100 vehicles near its eastern terminus in Rockport to a maximum of 19,000 vehicles near I-5 at Island Crossing.The Stillaguamish and Sauk rivers were traditionally used by the Sauk-Suiattle peoples, who traversed them in boats and also used parallel overland trails.