How can my adopted daughter find her birth mother?

My adopted daughter is now 17 years old and for several years has been expressing an interest in finding her birth mother, and possibly whatever other relatives she can locate. She has had a lot of health problems and thinks knowing more about her genetics and bio family medical history might be helpful. We have a very good relationship and I want to help her do whatever she can to find them. What are the laws in San Diego relating to opening adoption records, and does anything change once my daughter turns 18?