2009 California Water Code - Section 46710 :: Article 3. Penalty For Delinquency

46710.  If any installment remains unpaid at the expiration of 60
days from the date of the order, it becomes delinquent, together with
the accrued interest thereon, and a penalty of 10 percent of the
amount of the installment and interest shall be added and collected
for the use of the district.