The North Portland Harbor is an Oregon waterway or channel in Multnomah County, specifically in Portland. An anabranch, about 5 miles (8 km) long, of the Columbia River, it separates Hayden and Tomahawk islands from the mainland. Flowing generally northwest, the channel rejoins the main stem slightly upstream of Kelley Point Park and the mouth of the Willamette River. The Interstate Bridge carries Interstate 5 (I-5) over the channel, and farther downstream the Oregon Slough Railroad Bridge carries rail traffic. The BNSF Railway crosses North Portland Harbor over the rail bridge.