I have to disagree with the naysayers out there. How low you go is up to you (and your craft of choice). Kayaks can go quite low. Pineview goes fine at 0.5' (playboat), 0.4' is a tad too rocky for me. Similarly, Bridges has lines through it atleast down to 0.4', don't think I've tried 0.3'. Low water does mean less play, but it's still a relaxing float. You really get odd lucks from the fishermen in Pineview when you come through at that level. Granted, at 0.5', I think I'm the only one running Pineview down. Poudre Park was surprisingly good at 1'. Good as in plenty of water and more river time, not necessarily lots of play.
Lower Mish is fine at this level (~3'), it is not remotely boney/shallow by any stretch for a kayak. For a raft it may be. That said, the surf on Bridges is much better right now. Generally the left side of Lower Mish has a deeper channel. At 1' Devils/Ouzel is getting a tad thin.
We have run Upper Narrows through BTO at 1.5' numerous times, it's all fun. When I started I listened to these folks say that Bridges wasn't boatable/worth it below 2', and that's all hogwash
I will grant you that if you have the abilities to run the Narrows, it will be much more fun (at least for me) once we hit 1.5-2'.
That said, despite my enjoyment of low flows, I still haven't tried Rustic's below 3'.
Oh, if you are not in the FC area, would I drive to the Poudre when it's at 1' to run Bridges? Likely not unless nothing else was running and I really wanted to get wet
(kinda like doing Numbers at 150cfs or Royal Gorge at 200).... Not that I haven't done those drives
So my personal cut off for Bridges is 0.4' or so. If you can run the Narrows, that is much more fun at that flow, but if you can't, or want a mellow run, Bridges is perfectly fine. Plus you get to practice you rock avoidance!
(keep thinking light thoughts and you're good)