Cottage Grove and part of the eastern slopes of the Oregon Coast Range, begins in Douglas County and flows north to join the Middle Fork about southeast of Eugene. The elevation at the source of the mainstem Willamette is above sea level. Eugene–Springfield to Albany At the Willamette's source, the confluence of the two forks, is on the right and Franklin Boulevard is on the left. Interstate 5 (I-5), co-terminous with Oregon Route 99 (Pacific Highway), is also on the left bank slightly further from the river than Franklin Boulevard. For its first , the river flows north. It passes Willamette Heights Park, which is on the right, then enters the city of Springfield. The river then flows under a Southern Pacific Railroad bridge and under a bridge carrying Business Route 126 (Main Street); Millrace Park is on the upstream side of the second bridge, and Island Park is on the downstream side, both on the right. The unincorporated community of Glenwood is on the left. Turning sharply west at river mile (RM) 185 or river kilometer (RK) 298, the river flows by West D Street Greenway in Springfield, which is on the right, before passing under I-5 and turning northwest and entering Eugene. On the river's right beyond I-5 is Alton Baker Park, and on the left is Route 99, coterminous with Business Route 126. Along this stretch, the Willamette flows under the Knickerbocker Bicycle Bridge, the Dave and Lynn Frohnmayer Pedestrian and Bicycle Bridge (formerly the Autzen Bicycle Bridge), and the Peter DeFazio Bridge before reaching the Ferry Street Bridge, which carries Coburg Road. The river then passes Skinner Butte Park, which is on the left, and under Interstate 105 (I-105). Turning north, the river flows between East Bank Park on the right and West Bank Park on the left and passes under the Greenway Bike Bridge and then the Owosso Bike Bridge before passing under Oregon Route 569 (Beltline Highway) and leaving the city. Just downstream of the highway, Dedrick Slough enters from the right and then Dodson Slough, also from the right, before the river flows around Confluence Island and receives the McKenzie River from the right north of Eugene and from the Willamette's mouth. Meandering north, the river receives Spring Creek from the left about later, then flows around Marshall Island before reaching Linn County at about RM 167 (RK 269). For about the next