Flows in the Box Canyon are 495 cfs. Fishing in the Box Canyon has been consistent. Nymphing has been very good. I would suggest smaller bead heads and in the deeper runs you may need some split shot to get a deep enough. A #16 red zebra midge with a #18 red neck has been very good. As always smaller black rubber legs and a San Juan Worm will also work well. I really like to swing streamers this time of the year. If you enjoy spey fishing or want to get into the trout spey game, this is a great time of the year to do it. I like to wait for a day when temps get above freezing and are somewhat tolerable. I will access the river at the dam and fish down to the pump house. I like to fish smaller sculpin patterns or zonkers. Cast across let your streamer swing. Throw some mends into your swing to slow it down and hang on. When the strike comes it’s usually a violent affair. As far as equipment goes I like the sage one 3110-4 3 weight. I use the Rio 275 grain Skagit Max short and the Skagit Mow Medium Tips kit. Accessing the Box Canyon with a vehicle is over for the year. Walking in or snow shoeing in is the way to go.
Keep an eye on the weather. Last week when the temps dropped down below zero there was plenty of ice, making fishing next to impossible. However it has warmed up some and while there is some bank ice but the river as of today is looking great. Access with a boat can become an issue this time of the year so be prepared. There is snow in the forecast this week so the access at Ora Bridge may not be an option. I would scout your take out access before launching the boat. Again I would use smaller beads and streamers. There are also some amazing runs for the spey game on the lower Henry’s Fork.
The South Fork has been consistent if you’re nymph fishing. Access has become an issue on the upper end. Spring creek is do-able but Chains and lots of rope are a good idea. Another storm or two and the bridge access will be plowed in. The Conant access is also going to require chains and lots of rope. The flows are around 5000 cfs so that really opens up some wading options. I would stick with smaller bead heads and rubber legs. It’s always a good idea to have some streamers handy and remember to slow down the presentation this time of the year.