Tricos are appearing up and down the river. Fish for responding trout from 8AM to Noon which best time for having less stress for those caught, played, then released. The worst time for trout reacting to these actions is 4 PM to dark. In between these two periods, presenting ant and hopper patterns can bring action.
Flies to fish:
From 8 AM to mid day is the best time to fish anywhere on the river because water temperatures will be at their coolest.This goes well for the upcoming trico emergence which happens during mornings. Because water temperatures are highest then fishing from 4 PM on into evening is when water temperatures are at levels around those that are stressful to fish caught and played. Smoky air is like a blanket and means land and water cannot radiate heat off as quickly as can clean air. Therefore streams such as the Henry’s Fork hold daytime high temperatures longer. Strong winds can clear the air, but at the same time can limit aquatic insect emergence.
Do trout a favor by considering limiting fishing from first light until 2 PM because of rising water temperatures. This especially applies to where the river runs through open areas such as Last Chance through Harriman and Ashton Dam to Chester Dam. Bare, rocky canyon areas, like Warm River to Ashton, heat up more quickly and hold heat longer that forested canyons (i.e. Cardiac) areas through which a stream runs As summer advances, ant and grasshopper patterns will become increasingly effective for taking trout presented along all shorelines. In Box Canyon, hopper-dropper, two nymph rigs, rubber leg and fly rod jig patterns fished deep can bring action.
Flies to fish:
Summer doldrums are impacting the lower river, while cooler AMs and thunder shower potential help in keeping fishing success reasonable on the upper river. Also helping are growing stream side terrestrial insect populations (especially ants!). Algae is beginning to show in Island Park Reservoir and could impact water quality in the out flow. Water temps are generally such that dissolved oxygen concentrations are above the five mg per liter stress level for trout. Nevertheless consider minimizing fishing after three or four PM because this threshold could be approached and recovery of a caught and played trout impacted.
The major mayfly hatching period is coming to an end but will resume in a smaller form later this summer. AM spinner falls could bring some fishing action. Summer weather is bringing on the terrestrial insect season along the entire river. Good water quality reigns supreme, but daytime water temperatures are getting high. Plan to fish the lower river early and late in the day for quite some time now. Thunder storm threatening days are predicted for later this week. These could improve what is left of mayfly activity. If you can tolerate the recreationists in Box Canyon, two nymph rigs and rubber leg patterns fished deep can bring action. So can ant patterns presented along shorelines.
Flies to fish:
Fish survival throughout this river and any other depends so much on water temperature during summer. That is because of the inverse relationship of dissolved oxygen to water temperature. In other words, the higher the water temperature the lower the dissolved oxygen content. This concentration below six milligrams per liter of water brings on difficult survival conditions for salmonids. The Henry’s Fork has locations where this level is approached during afternoon hours, and when that temperature is nearing 70 deg. F. or more, it is time to find cooler water in which to fish. Salmonids caught and played at this temperature level and higher have more recovery difficulty induced by the stress of being caught and played, and the larger the fish the more difficult recovery becomes. Thus consider using a thermometer to check afternoon water temperatures wherever you are on the river, and give the ” bows, cutts, brookies, browns, and even whitefish” a break by moving to a cooler water location.
Henry’s Fork Foundation has another river cleanup coming up on July 30th from 9am-3pm. We will be starting at Ora bridge in Ashton, then stopping at access sites such as Chester, Fun Farm, Del Rio, Bubble Land, and Red Road. If you are interested in participating, please let me know! Lunch will be provided as usual, and we can provide transportation for a limited number of volunteers.
Best,
Jasper
–
Jasper Davis (she/her)
Outreach and Communications Coordinator
Henry’s Fork Foundation
P.O. Box 550
Ashton, ID 83420
office: 208-652-3567
cell: 480-993-8694
The major mayfly hatching period is coming to an end but will resume in a smaller form later this summer. Summer weather is bringing on the terrestrial insect season along the entire river. Good water quality reigns through the entire river at least above Beaver Dick Park. Plan to fish the lower river early and late in the day. AM spinner falls could bring some good fishing action. Best fishing on the upper river will be during mostly cloudy, thunder storm threatening days.
Flies to fish:
Bear Gulch
The increase in flow from Island Park Dam is to provide more water into the Crosscut Canal leaving the river at Chester Dam and going to the lower Teton River thus providing irrigation water to in that area.
For the best fishing success on the lower river, fish early in the day or during evenings. With oncoming even warmer weather terrestrial insects will be active both times. If you are exploring shallower water, consider wading wet. One thing about hot, dry weather, it brings on terrestrial insects. So survey your ant, beetle ad hopper patterns. Anywhere on the river, you are going to need them soon!
Cool Water Prevails in the Tubs
Presently, flavs and PMDs make up the major mayfly activity throughout the river. Notice that the size of PMDs is diminishing to make dun, emerger and spinner patterns reduced to the 18-22 range best to simulate them. Brown drakes are hatching from upstream slower waters but are well past their peak in numbers. Water quality is good nearly throughout the river except below St. Anthony where temps up to 70 deg. F. are present. Speaking of warm water; with hot weather coming next week, the river below Ashton Dam will warm to the point that daytime hours will limit fish activity making early and late in the day the times for good fishing. This change will eventually happen on the upper river. Consider that not only warming air but also bright sunny times contribute to making this change. The positive aspect of hot sunny days is that they will bring on the terrestrial insects throughout the river. Check your stock of terrestrial insect patterns!
Mayflies still reign supreme along the entire river. Drakes are still around, PM flavs are hatching, PMDs are throughout the river existing as emergers on through spinners. Caddis activity peaks in the aternoon, and a few golden stoneflies remain. Bring life cycle patterns for each and you will experience good action. In Box Canyon and lower Coffee Pot below the rapids dropping a nymph pattern under such as your favorite golden stonefly adult pattern. Be patient with your fellow fly fishers in high use areas and tolerant of recreational folks a many of them have yet to develop an on the water etiquette..
Water quality was good to excellent in all measures in all river reaches yesterday. Clouds and cooler air temperatures kept water temperatures below 70 degrees everywhere except at Parker. Daily minimum dissolved oxygen concentrations were higher yesterday throughout the watershed than over the past 4–7 days. Hatch timing is average for the date at all locations except Island Park Dam, where it is about one day behind, and St. Anthony, where it is one day ahead. Given a forecast of near-average temperatures for the next week, I do not expect any substantial change in overall aquatic insect development rates over that time period.