Shawn,
This coming summer may be a particularly tough one for finding internships, especially paid ones, so don't neglect the local possiblities.. Your best bet may be working thorugh the local ACHE chapter in the georgraphic area(s) that interest you. Some chapters are active in identifying opportunities such as you mentioned while others may represent a point of contact for further networking. That you are starting now is all to your advantage and really impressive.
As you start speaking with potential hosts, be clear on what is expected of them by your program in terms of evaluation and reproting, if any.