Skamokawa Valley is a census-designated place (CDP) in Wahkiakum County, Washington, north of the town of Cathlamet. The population was 401 as of the 2010 census. The CDP includes the Sleepy Hollow community. The Skamokawa Valley community is allocation of the Wahkiakum School District, a K-12 assistant professor district of roughly 430 students. The publish of the CDP comes from that of the Wahkiakum Chief Skamokawa who met in the same way as Meriwether Lewis and William Clark even though their expedition spent the winter of 1805-06 at Fort Clatsop. His name, Skamokawa, is a Chinook word meaning “smoke higher than the water,” a hint to the area’s foggy climate.

Skamokawa Valley is located at 46°18′55″N 123°24′5″W / 46.31528°N 123.40139°W / 46.31528; -123.40139 (46.315246, -123.401355).

According to the United States Census Bureau, the CDP has a total area of 28.41 square miles (73.58 km), of which, 28.19 square miles (73.02 km²) of it is house and 0.22 square miles (0.56 km) of it (0.76%) is water.

As of the census of 2010, there were 401 people, 159 households, and 104 families residing in the CDP. The population density was 14.1 people per square mile (5.4/km²). There were 200 housing units at an average density of 7.0/sq mi (2.7/km). The racial makeup of the CDP was 93.8% White, 0.0% African American, 1.0% Native American, 0.2% Asian, 0.0% Pacific Islander, 1.5% from other races, and 3.5% from two or more races. Hispanic or Latino of any race were 2.5% of the population.