Riverside is a census-designated place (CDP) in Umatilla County, Oregon, United States.

According to the United States Census Bureau, the CDP has a total area of 0.6 square miles (1.6 km2), all land.

There were 82 housing units at an average density of 137.6 per square mile (53.1/km2).

26.9% of all households were made up of individuals, and 11.5% had someone living alone who was 65 years of age or older.

About 4.7% of families and 3.9% of the population were below the poverty line, including none of those under the age of eighteen and 11.1% of those 65 or over.