2009 California Water Code - Section 23850-23851 :: Article 1. Supplemental Assessments

23850.  If the assessments levied upon land in an improvement
district are insufficient to pay the cost of improvements or the
warrants issued for the improvements, a supplemental assessment shall
be levied upon all of the land in the improvement district
sufficient to pay the cost or the warrants.

23851.  The procedure followed in making the supplemental levy shall
be substantially the same as for making the original levy, except
that no petition is required.