Service Dogs at Apartment Complex with no pet policy in effect

[Ramon Pena Alvarado]

We have an apartment complex in Denver, Co. We established a NO pet policy many years ago and recently a tenant secured a Service dog because of a trauma she suffered. Im not against dogs but...other tenants are constantly questioning me as to why they can't have a dog since my traumatized tenant can. 

I understand Service Dogs are protected under Federal Law and I can be sued and probably lose if I demand she leave. 

My question is:

1. Has anyone dealt with this situation and how?

2. Can I charge her a non refundable pet deposit and what amount is fair?

3. She is now - month to month...Can I give her a 30 day vacate and not break any Federal laws??

Thank You...