Backside Chehalis

The Chehalis River mouth is in Grays Harbor, near Aberdeen.

The Chehalis River is a river in Washington State. It originates in several forks in southwestern Washington, flows east, then north, then west, in a large curve, before emptying into Grays Harbor, an estuary of the Pacific Ocean.


The Chehalis River begins at the confluence of the West Fork Chehalis River and East Fork Chehalis River, in southwestern Lewis County. From there the Chehalis flows north and east, collecting tributary streams that drain the Willapa Hills and other low mountains of southwestern Washington. The South Fork Chehalis River joins the main river a few miles west of the city of Chehalis. The Newaukum River joins the Chehalis River at Chehalis, after which the river turns north, flowing by the city of Centralia, where the Skookumchuck River joins. After Centralia, the Chehalis River flows north and west, collecting tributaries such as the Black River, which drains the Black Hills to the north, the Satsop River and Wynoochee River, which drain the southern part of the Olympic Mountains. The Wynoochee River joins the Chehalis near Montesano, after which the Chehalis River becomes increasingly affected by tides and widens into Grays Harbor estuary. The city of Aberdeen lies at the mouth of the Chehalis River. Just east of Aberdeen, the Wishkah River joins the Chehalis, and just west, between Aberdeen and Hoquiam, the Hoquiam River joins. At this point the river has become Grays Harbor. Before the estuary of Grays Harbor empties into the Pacific Ocean, the Humptulips River joins.

Major FloodsEdit

December 3, FloodsEdit

During the December 2007 Pacific Northwest storms, a twenty-mile stretch of Interstate 5 was closed between exits 68 and 88 because of flooding from the Chehalis River, causing the roadway to be under about 10 feet of water. The recommended detour added about four hours and 280 miles. It was not expected to reopen for several days. However, upon breaching a dike on Dec. 5, 2007, the water receded quicker than anticipated. Repairs to the roadway are scheduled to occur as soon as possible. Amtrak train service between Portland, Oregon and Vancouver, British Columbia was also disrupted. Washington governor Chris Gregoire declared a state of emergency on December 3.

January 7, 2009 FloodsEdit

During the January 7, 2009 Pacific Northwest storms, a twenty mile stretch of Interstate 5 was closed between exits 68 and 88 because of flooding from the Chehalis River, causing the roadway to be under several feet of water. Since the main east/west mountain passes were also closed during this event, the flooding from the Chehalis river essentially cut off traffic to the Puget Sound area and no detour was available.