On July 13, Jerry Brown signed into law SB 222 which makes the sources of revenue supporting voter approved CA School Bonds statutory liens and protected from bankruptcy. 

In most cases, the valuations of the taxable property in these School Districts is 100 times the amount of debt outstanding and bondholders have a senior claim (even to the mortgage bank) to their tax levy on this property. 

The rating agency's rating criterion still includes the School Districts General Fund as well as the flexibility of their School Board; neither of which have any bearing on the sources  that support these bonds. 

The rating agencies are wrong in their methodologies and these security types should have AAA ratings.