Riverside, WA -- U.S. town in Washington Population (2000): 348 Housing Units (2000): 153 Land area (2000): 0.893474 sq. miles (2.314088 sq. km) Water area (2000): 0.078962 sq. miles (0.204510 sq. km) Total area (2000): 0.972436 sq. miles (2.518598 sq. km) FIPS code: 58795 Located within: Washington (WA), FIPS 53 Location: 48.502830 N, 119.508718 W ZIP Codes (1990): 98849 Note: some ZIP codes may be omitted esp. for suburbs. Headwords: Riverside, WA Riverside