State governments set minimum amounts of insurance coverage by law for all licensed drivers.
I know the Boy Scouts of America sets minimum coverage levels for leaders or parents who will be transporting youth to events.
If you will be transporting children in your personally owned vehicle (POV) I would expect that the state agency specifies minimum levels. These levels should be spelled out in regulations. And should have been made clear when you started in your current position. It is also possible that they were recently adjusted.
I would ask if your insurance is considered primary or secondary.
I would also research what your auto insurance company requires when using your POV for work. Is that extra coverage? Do they not cover you if the mileage dedicated to work is greater than X percent of your annual mileage?