The district says that it is trying to collect more than $20,000, and that other methods to get parents to pay have not been successful. Four parents owe at least $450 apiece.
The letter claims the unpaid bills could lead to dependency hearings and removal of their children for not providing them with food.
"You can be sent to dependency court for neglecting your child's right to food. The result may be your child being taken from your home and placed in foster care," the letter read.
After complaints, district officials announced they plan to send out a less threatening letter next week.