Child Protective Services took the children into custody.
Court papers say Ingram told police she did not want to get "dope sick" in front of family, so did not ask for help with the kids.
Marysville police arrested Ingram and Knapp-Mills for investigation of criminal mistreatment.
In court Monday, the deputy prosecutor did not request a probable cause finding to keep them in jail, so a judge released them.
A spokesman for the Snohomish County Prosecutor's Office told KIRO-TV by email that the facts presented by police "did not support probable cause for the specific charges they were booked on."
Prosecutors still have the option of filing criminal charges.