There are plans to significantly increase the flow out of Island Park Dam on July 22nd-23rd in order to test turbines at the Chester Dam low head hydro facility during July 23rd-24th. This short but significant increase is sure to temporarily impact fishing on much of the river. Final figures on flow will not be established until Monday, July 21st. When we see more information on this action, we will post such here.
As is usual this time of year, fishing on the river from Ashton Dam downstream has slowed as waters have warmed significantly. Early AM spinner falls and evening caddis activity can bring some action. Also try streamers at twilight.
Drake hatches in the Last Chance-Harriman stretch are pretty much over. Now it is on to flavs with PMDs. During these hot dry days fishing early morning spinner falls with your favorite rusty spinner pattern is not only pleasant but productive. The river below Ashton Reservoir is warming meaning slowing action. Evening caddis activity and AM spinner falls is best time to fish. Below Chester Dam irrigation demands have lowered and warmed the river to the point it’s hardly worth a visit. There is some action on the Flat Ranch section of the Henry’s Lake Outlet section for those folks using PMD life cycle and dry damselfly patterns. But if a bigger early season flush had taken place a lot more fish would be present.
The Last Chance-Harriman State Park reach of the river is crowded, and rightfully so. One way to beat the crowds is to try the early morning or evening spinner fall. Green drakes and PMDs are going strong, and caddis are everywhere. Any day now brown drakes in the evening will become significant. On the lower river, Warm River to Ashton and below Ashton Dam, caddis and PMDs and diminishing golden stoneflies attract fish. As with the upper river, ant and beetle patterns fished near banks will interest fish. It looks like this will be a lean year for gray drakes in the evenings, but this time of day can be great for presenting streamers around stream side cover out of direct sunlight.
Green drakes are beginning to fade out on the lower river. Not many gray drakes have made an appearance to date. Hopefully that is changing. PMD and caddis life cycle patterns are working just fine.
On the upper river green drakes are coming on but not yet peaked. PMD activity is good and attracting fish. Flow out of Island Park Dam was raised on Thursday from 1000 cfs to 1160 cfs and is holding there. There are likely as many fly-fishers as fish in the Last Chance-Harriman State Park stretch of river with fewer visits in the Harriman East, Riverside and Coffee Pot stretches.
PMDs, Green Drakes and flavs are bringing fish up on the lower river. We have not heard much to date about gray drakes emerging in significant numbers. Flow out of Island Park Dam was raised to 1000 cfs last Friday. It has been stable since then meaning better conditions for good green drake activity, and we have had a few reports saying fishing success has improved around Last Chance as a result. The river in Harriman State Park opened to fishing yesterday. We have not heard much of success yet, but we will soon.
Flow out of Henry’s Lake, which lately features slow fishing, is up to 80 cfs. This means some reasonable fishing could be had in the Flat Ranch portion of the river. Green drakes, PMDs, and caddis activity will bring fish up. Much better fishing would have resulted had a flush of around a couple hundred cfs happened earlier this spring.
Seems like everything fishing is early this year, and that is the case with Henry’s Fork green drakes. Both have been out for a while on the lower river. Now they are out in good numbers on the upper river. Plenty of PMDs, too. The Harriman State Park section of the river opens Monday, June 15th, and you can bet that with good numbers of green drakes out now fish will be keying on them. But here’s a tip: consider trying a big dry stonefly pattern. Want to know why? Yes the stonefly event is over, but a few still hang around, and wind (like we had yesterday) blows them into the Harriman part of the river from Box Canyon above and Cardiac Canyon below. The older fish know what they are. Need I say more? Same strategy works anywhere canyon reaches holding big stoneflies are adjacent to habitat favored by green drakes; ie Firehole River, Lewis River, Fall River Basin streams. Not many gray drakes on the lower river, yet. Let’s see what kind of numbers will happen in this low water year.
By having the Henry’s Fork running at almost 500 cfs lower flow then normal for this time of year, the hatches are beginning to occur faster from Warm River and down. Pmd’s spinner falls in the morning have been quite successful from about 10 in the morning to about 1 in the after noon. Also, caddis have been prominent in mornings and evenings. Although now with the sighting of Green Drakes, I would make sure to have them along in my box. Additionally, I would also not be afraid to fish a dry dropper with a golden stone and a small nymph. Next, the dry flies I would take are Super Chernobyl Brown size 10, Improved X-Caddis Yellow size 14 and 16, Green Drake Wulff size 10, Harrop’s Rusty Biot Spinner size 16 and 18, and finally a Harrop’s CDC PMD Biot Spinner size 16 and 18. Then for nymphs I would use a Bennet’s Brown Rubber Leg size 8, Copper John Red size 16, and Uv2 Mayfly nymph size 16.
The Henry’s Fork is currently providing some of the best fishing in the area. Let’s look at what it offers bottom to top. Below Ashton Dam PMDs and caddis life cycle are bringing action, but after the peak stonefly activity came by a few weekends ago, fish are once again looking for the big bugs, and golden stones are satisfying them especially in afternoons. Cloudy PMs bring on the BWOs. It’s the same story from Warm River to Ashton, so go with your favorite BWO, PMD, caddis, and golden stone patterns. But consider that rubber leg patterns have also been effective. Cardiac Canyon offers some great fishing, not just to those folks floating through, but also to those walking in from the Bear Gulch, Mesa Falls, Hatchery Ford, or Riverside points. Add yellow sally patterns to the “what’s effective” bunch discussed above for the Cardiac Canyon section. The river is lower than normal here making wading a bit less dangerous. Nevertheless, take care. PMDs are coming on at Last Chance to join cloudy day BWOs, caddis, and dwindling March browns. Water coming out of Island Park Dam has been a low but steady flow of around 350 cfs for many days now. This means walk-in wading makes a better choice than dinging up that boat. In some ways this is better for encountering fish currently taking big dry stoneflies: you get more than one chance at them and can spend more time pin-pointing select locations. Further up the river, walking into the Henry’s Lake Outlet on the Flat Ranch Preserve will get you into fish as well as relative solitude. These are mostly cutthroat escapees from Henry’s Lake with a few hybrids mixed in. Remember that these are lake fish, and at first will feed on food forms familiar to them in the lake. So do not overlook leech and streamer patterns. When these fish feed increasingly on what is available in the river, spend more time with PMD and caddis life cycle patterns, and hopefully in two weeks, green drake life cycle patterns. Fish here are not present in huge numbers because a 200-300 cfs flush out of the lake was not performed earlier and flow out of the lake has been around 50 cfs for several weeks. But there are always some big surprises in the river flowing through this Ranch.
The big stonefly hatch is about over except for some getting Coffee Pot area fish’s attention. Golden stones are the way to go now. And don’t forget that after about a week of normal weather those big dry stonefly patterns can be effective again. For now, presenting caddis life cycle patterns can be effective in most of the waters with gradient. That means Cardiac Canyon waters and Warm River to Ashton.