California Code, Public Resources Code - PRC § 7534

The county treasurer shall retain all money arising from the sale of swamp and overflowed lands and place it to the credit of a separate trust fund or trust account. He shall compute interest on all sales of such lands from the date of the approval of the survey or the date of the certificate of location to the first day of January following such date, or, if for lands already purchased, up to the first of January following the day upon which the interest falls due, after which time all payments of principal and interest fall due on the first day of January.