Jurupa Valley, California. From Wikipedia, the free encyclopedia. Jurupa Valley is a city in Riverside County, California. On March 8, 2011, voters approved a ballot measure, designated as Measure A, to incorporate the area into its own city; as a result, the area has been an incorporated city since July 1, 2011. The city of Jurupa Valley covers approximately 43.5 square miles (113 km 2), and has an estimated population of 98,842.