Cal. Water Code § 8165

The legislative body of the county or city which conducted the proceedings for the organization of such drainage improvement districts may do all of the following: (a) Order the cancellation of any special assessment district tax levied upon property within such special assessment districts subsequent to the date of transfer and any unpaid installments of specific or direct assessments becoming due or delinquent subsequent to the date of transfer. (b) Refund and adjust all payments made upon such installments becoming due or delinquent subsequent to the date of transfer. (c) Cancel any and all installments of specific or direct assessments levied to retire bonds issued under the Improvement Bond Act of 1915, due or delinquent prior to the date of transfer in any case in which the principal and interest upon such bonds maturing prior to the date of transfer have been paid and the bonds so matured have been canceled and retired.