I played rage for a little bit, then downloaded the dlc for the wasteland sewer missions and when I started my game there was no notice or journal update or anything. So where is it? Do I have to discover it on my own?

The first entrance is across the street from the arc that you exit at the start of the game. There will be a man standing under a red tent.

Cool you rock lou thnx!

There are like 4 old threads about sewer missions, everything you need to know.