How can I take my sisters baby?

okay here is the deal. My sister is on drugs ( pain pills, oxy, meth, needels) whatever she can get ahold of. She has a 6 month old girl that me and my parents love dearly. But we cant seem to get any help by taking the baby away, we just dont want nothing to happen to her, we could careless about my sister anymore. Also she has been in and out of jail allready and she is just 18. We done called dhs and no help there. WHAT CAN WE DO?? WHAT RIGHTS DO WE HAVE??