Current Conditions:
The East Gallatin can be a nice wintertime option. Fish are most active in the afternoons and nymphing will generally outproduce other methods. Trout become highly concentrated in the winter so hunt for just the right water and then slow things down and focus your attention on "winter lies". Expect trout in the slower and deeper runs where they don't have to work hard in the cold water. Smaller nynphs like baetis nymphs and midge larva are best and try spring creek methods like yarn indicators to detect the subtle takes since fish aren't moving aggressively to the fly this time of year.
The Month Ahead:
The East Gallatin will remain in a winter mode for a few more months. Pick the nicer days and focus your efforts in the few hours after lunch when fish are most active.