The CEQA Statute and Guidelines both contain provisions outlining what types of projects are exempt from environmental review. There are dozens of exemptions, however, that are listed in other provisions of the California codes that can be difficult to find. On June 6, 2018, the Governor’s Office of Planning and Research (OPR) released a helpful technical advisory listing over 50 CEQA exemptions that are not codified within CEQA itself. The advisory does caution that the list is not exhaustive. Below is a link to access the technical advisory.
http://www.opr.ca.gov/docs/20180606-Tech_Advisory_CEQA_Exemptions.pdf