Cal. Water Code § 35520.34

The board, pursuant to a resolution entered in its minutes, may distribute among the landowners of a drainage service area any funds in the treasury belonging to the service area which were collected on an assessment on which no bonds are outstanding or collected by way of interest or penalties on the assessment or by the rental, sale, or redemption of delinquent land under the assessment and which appear to the board to be greater than required to meet all obligations incurred or to be incurred for the purposes for which the assessment was levied. The distribution to the landowners shall be made in the proportion that they were assessed on the assessment.