CEQA only applies to projects that require discretionary approval by a government agency. A discretionary approval requires the use of judgment on the part of the approver. For example, if you want to change the zoning on your property to subdivide the property for a housing development, a discretionary action would need to be taken by the Board of Supervisors. This simply means that the Board of Supervisors has a choice to either approve or disapprove your request.
CEQA also applies to ministerial (non-discretionary) projects, however may qualify for an exemption as allowed by CEQA. A project requiring only ministerial approval simply involves a comparison of a project with specific standards or checklists and checking for compliance. For example, a County Building Department may check your house plans against electric and plumbing standards to make sure that the plan complies with adopted safety and sanitary regulations. Generally, the issuance of a building permit consistent with zoning and other land-use regulations is a ministerial action.