Cal. Water Code § 42280

If the board of any district fails to complete and file its report within 10 years from the date of the filing of the order of the department declaring the district duly organized, the project of the district shall be deemed abandoned and the board shall within 90 days thereafter pay all outstanding debts and claims against the district and shall within that time remit to the assessment payers of the district in proportion to the amount paid by the assessment payers on the last call or assessment levied by the board the balance of any funds then remaining with the treasurer of the district or to its credit with the county treasurers of affected counties.