Cal. Gov. Code § 54782

Bonds issued by the county are legal investments for all trust funds, the funds of all insurance companies, banks, both commercial and savings, trust companies, executors, administrators, trustees and other fiduciaries, for state school funds and for any funds which may be invested in county, municipal or school district bonds. The bonds are securities that may legally be deposited with, and received by, any state or municipal officer or agency or political subdivision of the state for any purpose for which the deposit of bonds or obligations of the state is now, or may hereafter be, authorized by law, including deposits to secure public funds.