The Riverside County TLMA now offers most of their GIS data online for free. You can download it by following this link: http://www.tlma.co.riverside.ca.us/online/content/gis_downloads.aspx
You will need access to software that can read ESRI file Geodatabases in order to use it however.
You will need access to software that can read ESRI file Geodatabases in order to use it however.