Clatsop Plains

Clatsop Plains
Aerial view of the northern Clatsop Plains
Location	Clatsop County, Oregon
Coordinates	46°04′04″N 123°55′51″W / 46.067884°N 123.930696°W / 46.067884; -123.930696Coordinates: 46°04′04″N 123°55′51″W / 46.067884°N 123.930696°W / 46.067884; -123.930696
Age	Quaternary

The Clatsop Plains are an area of wetlands and sand dunes between the Northern Oregon Coast Range and Pacific Ocean in northwestern Oregon in the United States. They stretch from near the mouth of the Columbia River south to the vicinity of Tillamook Head near Seaside. The plains are drained by several coastal rivers include the Skipanon River and the Necanicum River, which flow parallel to the coast and empty into the Columbia at Youngs Bay near Astoria and into the Pacific Ocean near Seaside respectively. At the time, the Lewis and Clark expedition recorded a different river draining the plains which entered the Pacific near the current day Camp Rilea Armed Forces Training Center. Research, 200 years later in 2005, seems to have confirmed this by locating an old river channel.

The plains are named for the Clatsop tribe of Native Americans who lived in the area at the time of the arrival of Europeans and European Americans by ship at the end of the 18th century and by land at the beginning of the 19th century.

These plains were developed from sand filling in the shoreline during the late Quaternary age. The northern portion is a result of the creation of the south jetty on the Columbia River built in 1885. Within the plain are several lakes including Cullaby, Sunset (Neacoxie), Smith, and Coffenbury. The latter three are filled by groundwater and not local streams or rivers.