Chehalem Creek enters from the left, and then the river flows around Ash Island, where it receives High Water Slough from the right. Downstream of the island, the city of Newberg is on the left, from the mouth. At Newberg the river, which has been meandering north from Eugene, turns sharply east, passes under a pipeline bridge and, about later, under Oregon Route 219. It then receives Spring Brook from the left before reaching part of the Willamette Greenway on the left, and Champoeg State Park, on the right. Champoeg Creek enters from the right at RM 45 (RK 72) and Ryan Creek from the right less than later. Then the river leaves Yamhill County and becomes the border between Clackamas County, on the left, and Marion County, on the right, slightly upstream of the unincorporated community of Butteville, which is on the right. From Champoeg to Wilsonville, Wilsonville Road runs roughly parallel to the river and to its left, and from Butteville to Wilsonville, Butteville Road follows the river and to its right. About below Butteville, the river ceases to be the border between two counties and flows entirely within Clackamas County. Corral Creek enters from the left about from the mouth, and then the river reaches Wilsonville and Wilsonville City Park, which are on the left. The river then flows under the Boone Bridge, which carries Interstate 5 (I-5), and receives Boeckman Creek from the left about later. Newland Creek enters from the left and the Molalla River from the right at RM 36 (RK 58), where Molalla River State Park is on the right. About later, the river reaches the Canby Ferry, which carries vehicles across the river between Canby to the right and Wilsonville and Stafford to the left. The Willamette then flows by Walnut Eddy and Fish Eddy, where it turns sharply north again about from the mouth. From Fish Eddy to Oregon City tracks of the Union Pacific Railroad run roughly parallel to the river along its right bank, and from Fish Eddy to Gladstone, Oregon Route 99E runs roughly parallel to the river, also along the right bank. Below Fish Eddy, the river passes Willow Island and New Era Bar before receiving Beaver Creek from the right, near Sevcik Pond. Below Beaver Creek, the river flows through the Rock Island Complex (Willamette Narrows) before receiving the Tualatin River from the left about from