She faces drug and child endangerment charges.
A resident of the home, Larry Dangelo, is also charged in the case.
According to the detective, Behrens took her son, Jason Bradford Jr., 2 years and 9 months old, and daughter Harley Bradford, 16 months, swimming the night of May 12. She said they all went to bed around 9 p.m., the children on a couch and she in a bedroom with Dangelo.
Sheriff's Detective Norman Hubbert said Behrens told them she saw her children on the couch when she used the restroom around 4 a.m., but four hours later, Jason came in and asked where Harley was. Behrens told the detective she fell back asleep, and neither child was around when she woke up.
"She went out to the back patio that overlooks the back yard and saw the children face-down in the pool," Hubbert said.
She ran down screaming to the pool and pulled them out, and the children were rushed to Grossmont Hospital, where Harley was pronounced dead. Jason was transferred to Rady Children's Hospital, but he also died.