Report September 25, 2017

Our weather began to change in a significant way this past Thursday.  Temperatures started to drop, clouds moved in and rain began to fall. This change turned a good Mahogany hatch into a great Mahogany hatch.  I went down to the river after work and found myself in the middle of the best Mahogany hatch I have ever witnessed. The hatch was as strong as any I have ever experienced and the fish were actively feeding on the freshly hatched duns.  Fish were up everywhere. As I stood there I found myself starting to feel sorry for those poor mayflies. It seemed to me that at least eight out of every ten adults floating down the river were eaten before they could escape to bankside cover. I started to wonder how they could continue to sustain their population with only twenty percent of the hatching insects making it to full blown adulthood. Now I am not going to tell you that every fish I saw feeding was a twenty incher. But, there were plenty of fish in the thirteen to fifteen inch size range with a few big guys mixed in.  The presence of so many medium sized fish in the river can only bode well for the coming years.  We have plenty of water in the reservoir this fall so we should have ideal flows throughout the winter providing the conditions necessary for good winter survival. These medium sized fish are the trophy fish of the coming years provided they survive the winter.  A few closing thoughts about presentation/technique.  I found that the fish wanted my adult Mahogany imitations floating as high and dry as I could possibly present them. After I caught a fish I had to tie on a fresh fly so that it would float in such a way as to give it the exact profile of a freshly hatched dun.  
Box Canyon:  The “Box” continues to produce very good fishing.  There has been excellent streamer and nymph fishing from just below the dam and throughout the entire canyon.  There has also been some decent dry fly fishing on the lower third of this stretch with BWO imitations.  A few fly suggestions would include red, black and brown Zebra Midges, Two Bit Hookers, black Rubber Legs, olive Sculpinators, LE Leeches, olive/white Barely Legals for nymphs and streamers.  A couple of adult baetis imitations would be Hi-Vis Baetis and Baetis Sparkle Duns. 
The “Ranch”:  The “Ranch” section of the Henry’s Fork is fishing very, very well.  We have a good Mahogany hatch going on and blanket baetis hatches. There are a couple of different types of baetis hatching so there are baetis of at least two different sizes on the water. There is a size #20/22 and a size #24/26.  If you are like me you think a size #20 is a challenge to fish most of the time but with those size #24/26s on the water I find myself hoping for the size #20 because it looks huge compared to those little guys.  The fish seem to be anticipating the hatches and when they come they are up and feeding. A few fly suggestions for the “Ranch” would include HOH Mahogany Last Chance Cripples, HOH Mahogany Biot Duns, Hi-Vis Baetis, Baetis Sparkle Duns, and CDC Throax BWOs.
Warm River to Ashton:  Pretty much the same as always. Lot’s of action for small to medium sized fish on dries, nymphs and streamers.  The browns are starting to get aggressive as they get into the spawning mode so the streamer fishing is picking up. A few fly suggestions for this section of the river are coffee/black and black Rubber Legs, King Princes, red Copper Johns, Beadhead Flashback Pheasant Tails, Parachute Adams, Hi-Vis Baetis, black Bouface, olive/black LE Leeches, Sparkle Minnows and olive Silk Kitty.
Ashton to Saint Anthony:  Streamer fishing is the name of the game on this section of the river.  The browns are on the move and they are chasing a well presented streamer or even a not so well presented one. There is also a good baetis hatch going on providing some decent top water action for the dry fly enthusiast.