The Port of Siuslaw is a district of over 700 square miles that includes the Siuslaw River watershed. The southerly boundary is at the Lane-Douglas County line and the northerly boundary is near Heceta Head. Going inland, the boundaries extend as far as Horton in the northeast, skirt Noti and Vaughn to the east, and continue southeast to an area just outside of Cottage Grove encompassing the Lorane area.
The Port of Siuslaw District covers over 700 square miles.