Cal. Gov. Code § 29303
This section does not apply to the sale by counties of bonds purchased as investments. Whenever any bonds issued by any county or by any school, drainage, or other district in any county, whose accounts are required by law to be kept by the county auditor and treasurer, are sold at a premium or with accrued interest, or both, the amounts received for the premiums and accrued interest shall be deposited in the debt service fund of the county or district unless it is expressly provided by law that they be deposited in some other fund.
Interest earned by investment of proceeds of bonds which are authorized after the effective date of the amendment to this section adopted at the 1963 Regular Session of the Legislature shall be deposited in the debt service fund of the county or district unless it is expressly provided by law that such interest be deposited in some other fund or unless some other disposition of such interest is authorized by the resolution which authorized such bonds. This paragraph does not apply to the proceeds of bonds issued by any school district.
Ca. Gov. Code § 29303