If you try the water (it’s a bit high because of downstream irrigation demands) from Last Chance through Harriman State Park the rusty spinner (size 14-20) is the “must have” fly. Afternoon caddis activity offers several types of insects, and hoppers are beginning to show. Fishing on the lower river is slowing down, but crowds have gone over to the South Fork
As water warms, look for increasing mayfly activity. Right now evening caddis activity is very good here, and nymph patterns presented through heads of riffles are working. With flow at the dam around 12300 cfs (13000 cfs at Heise, 5500 cfs at Lorenzo) water is where it should be but needs to warm a bit. Expect crowds at all boat ramps. There are stories of crowding and social situations on the icon water boat ramps and on the stream, seemingly more than in past years. Much of this situation can be understood because many other local outdoor activities such as concerts and outdoor workshops are cancelled except for fishing which tends toward social distancing. Add to this that metropolitan area folks coming here to escape covid-19 situations. So unusual crowding should be expected.
The Yellowstone River below the lake opened to fishing on July 15th, and crowds converged there to try for the large cutthroat. Streams in the northeast corner of the park are coming into good fishing condition, but for those of us in the southwest corner of the Greater Yellowstone area they are a near 200 mile drive and likely crowded on arrival. That makes Fall River Basin streams more attractive with respect to traveling, but you will have to walk further to approach them. Meadow reaches on these streams are drying and flows are bit lower than normal. That means stealth, long casts, and fine tippets are required for success. PMDs are decreasing and sallies are at minimal abundance with a few wind blown golden stones present. Traditional attractor patterns in moderate (#12-16) sizes will be effective. Be bear aware!
Same as the last report: Get to creek mouths and spring holes as early as possible. Use standard Henry’s Lake patterns with a slow retrieve of that intermediate line. If you start having success, expect company to surround you because a common Henry’s Lake practice is using binoculars to observe where fish are responding, then converge on that location to share the action.
The best fishing on the lower river is from Warm River to Ashton, but that section is beginning to turn to early and late in the day for the best results. PMDs, a few goldens and flavs are present with caddis providing PM action. Don’t forget to pitch a steamer pattern around overhead cover as the sun sets. Crowds have thinned everywhere on the river. Much of that is because of the activity on the South Fork. On the upper river nymphing seems the most effective way to action in Box Canyon where recreationists will share the water. Further downstream at Last Chance and Harriman crowds have thinned a bit and mayfly hatches are off their peaks. AM and PM spinner falls provide good action with standard rusty spinner patterns being most effective. PMD and decreasing flav activity provide some daytime action with a variety of caddis taking over during PMs.
You cannot go wrong on just about any small stream. The Teton River in the basin and its tribs have shaped up, for example. PMDs, (spinners and duns), isoperla stoneflies, and PM caddis activity are providing action with terrestrial insects yet to peak. Recreationists are present making early and late in the day the best time to fish with fewer interruptions. Expect to see increased use of the river by fly-fishers and floating recreationists for the reason given on other pages of this report. Because of this growing use, it may be time to seek the smaller streams in the area. They are too numerous to relate here, so get in touch with us because we keep track of their quality and can pass such info on to you.
Everywhere waters are warming up and in most waters damselfly activity has peaked. Go deep with 3 and 4 type sinking lines to get black or olive leech patterns down to cool waters where the larger fish have settled. A good line choice for getting and saying deep is the new Fathom Clean Sweep Slow sinking line by Rio. At its tip is a clear intermediate front end, followed with faster sinking S4 section, then an S2 running line section.
Flow below Mackay Dam has been around 350 cfs for weeks. That makes for stability. Now is the time of year when golden stones and western green drakes activities take place in the river. Most folks coming from over from Sun Valley will be fishing the river above the reservoir.
The upper Gallatin River is coming on with caddis , some PMDs and big stoneflies. As word of good fishing gets out visits will increase to the easily approached river adjacent to the highway. If you venture there and note filled parking areas, walk upstream on the Big Horn Pass trail a few miles to find more tranquility in the river running through the sloping meadow. Be bear aware!
If you live in the southwest corner of the Greater Yellowstone Area, why travel nearly 200 miles to fish the northeast corner of the park when the four major Fall River Basin streams (Bechler and Fall Rivers, Boundary and Mountain Ash Creeks), currently are in great dry fly shape and offer PMD, yellow sally, damsel fly, green and brown drake activity with oncoming terrestrial insect activity. In addition, Beula Lake at the top of Fall River offers some of the fastest fishing in the area. All one needs to do is walk a few miles to enjoy the best waters in Fall River Basin.