I've found it!

Okay, so the perfect way to train for an open water swim without having access to open water:
1. Public pool with lanes attached to main pool area, so you get the chop effect pushing you into the lane lines from 150 individual little fluorescent-clad kids belly-flopping right next to you.
2. Because of that same feature, you have to watch running into the other triathletes (oops, kids) that jump into your lane to "train" or "make you worry they're going to start sinking in your lane and you haven't had safety training in a while...".
3. Make sure you swim in a lane that the pool designers designated to create the current for the entire pool by putting a high-powered jet at one end, in the middle of the lane.
4. Always, always, wear foggy goggles so you can't see the kids jumping into the lane, the people swimming across it, or your hands in front of you.

I decided the public pool was a great place to train today, seriously, using these reasons. Happy swimming, everyone! :-)