Cal. Gov. Code § 57418

If any city has within its boundaries, at the time of incorporation, at least two-thirds of the assessed value of an assessable property formerly contained within a disincorporated city, it becomes the owner of all public property formerly belonging to the disincorporated city and that proportion of the debts, liabilities, and credits owned by or due to the disincorporated city as the value of the assessable property of the disincorporated city lying within the boundaries of the new city bears to the value of all assessable property formerly contained within the disincorporated city. The value is that shown by the equalized assessment roll in effect in the fiscal year in which the city was disincorporated.