Sauvie Islan, in the U.S. state of Oregon, is the largest island along the Columbia River, at 26,000 acres (105 km²). It lies approximately ten miles northwest of downtown Portland, between the Columbia River to the east, the Multnomah Channel to the west, and the Willamette River to the south. Much of the interior comprises water; Sturgeon Lake, in the north central part of the island, is the most prominent water feature. The land area is 84.82 km² (32.75 sq mi, or 20,959 acres). Most of the island is in Multnomah County, but the northern third belongs to Columbia County. The Sauvie Island Bridge (built 1950) provides access across the Multnomah Channel from U.S. Route 30.