The lowest that I have ever floated it was at 3.8 on the gauge height.Sorry I don't what that particular flow was,I always just look at the gauge height.At that level it can get to be a pain bangin your way down the river.Fished it a lot the spring before when it was open in March.The river was running consistently low then,usually around 4.5 to 5.5 feet,was not a problem.One thing to remember is that with the lower flows you may have to dodge more,but you also have more time to set up because you are not getting pushed around as fast.Hope this helps.