Are there alternatives to making notification by written letter to the individual?

Yes. The law provides for substitute notification (see Civil Code Section 1798.29(g) (3)) such that the notice must be made by email, website posting, and major statewide media (all three). Please refer to SIMM 5340-C РRequirements to Respond to Incidents Involving a Breach of Personal Information (PDF) for additional information about the criteria that must be met in order to make substitute notification.