daaangit--Bessie's advice is very good. However, if admission officials see a cryptic reference to "an ongoing illness," they may wonder what this illness is and if you are prepared for the rigors of college. Thus I suggest that you provide some additional information before you are asked (because you may
not be asked).
For more specifics, you might want to check out this recent "Ask the Dean" column:
Admission Advice for Student with an Anxiety Disorder
It's about Anxiety Disorder, but you'll find that it's appropriate for your situation, too.
You might want to tell your school counselor about your depression, if you're comfortable doing so. This will enable your counselor to put your grades in perspective when writing your college recommendation.