California Code, Education Code - EDC § 46391

Whenever any attendance records of any district have been lost or destroyed, making it impossible for an accurate report on average daily attendance for the district for any fiscal year to be rendered, which fact shall be shown to the satisfaction of the Superintendent of Public Instruction by the affidavits of the members of the governing board of the district and the county superintendent of schools, the Superintendent of Public Instruction shall estimate the average daily attendance of such district.  The estimated average daily attendance shall be deemed to be the actual average daily attendance for that fiscal year for the making of apportionments to the school district from the State School Fund.