We have reports of Sand Creek Pond #4 water temperatures in the low 70s in degrees Fahrenheit. Consider how tough this condition is on fish being hooked, played, then released. The bigger the fish, the tougher high water temps are on them.
Flow out of Palisades was lowered to 11300 cfs ( a bit below average for this date) yesterday. The irrigation season peak has been reached, so more flow reductions are likely. Riffle fishing is at the quality for which the South Fork is famed. For active mayflies there begin the day with small nymph patterns, graduating to emergers on first sight of rising fish, then with more surface activity switch to duns.
Major quality streams in the northeast portion of the park are now in good fishing shape ( green drakes, PMDs, PM caddis, sallys, terrestrial insects increasing) barring thundershowers that muddy the Lamar River in particular. The problem is that the easily accessed portions ( lower Soda Butte Creek, Slough Creek in meadow below the campground and the meadow just above it, Lamar River meadows) are crowded with visiting anglers. Getting to these great waters is also frustrating because of the massive tourist traffic on park roads causing delays which shorten ” Time on the Water.” Minimize these delays by traveling earlier in the day: the earlier the better. Rewards are lighter tourist traffic and the chance to be first on the water.
Compare this to equivalent or even better quality Fall River Basin streams in the diagonally opposite (Southwest) corner of the Park. These streams ( Fall River and Bechler Rivers, Mountain Ash and Boundary Creeks) have non-existent crowding, especially on walking as far as one would on Slough Creek and the Lamar River to find equal social conditions. And tourist traffic is always minimal. True, Fall River Basin streams are considerably more remote, about 25 miles distant, half over which is gravel, by road from Ashton ID. But therein lies the reason for their giving a better chance of tranquility and an even a better fishing experience.
The South Fork is doing what it is famed for this time of year. Flows are consistent, (12300 cfs out of Palisades Dam and at Heise, whereas normal flow is 12900 cfs), good hatches in the riffles, terrestrial insect importance coming, and a few big bugs still out above Conant.
The lower river, especially below Ashton Dam, is comfortable enough for swimming. For the river in the Island Park area it is soon time to break out terrestrial insect patterns. Flows in the river in the Flat Ranch Preserve are beginning to drop, so look for fish there to begin moving to the cooler river below. The flow there is dominated by the Big Springs outflow, so should be quite hospitable.
Streams in the northeast corner of the park are now in good fishing shape ( green drakes, sallys, PMDs, caddis). Slough Creek and the Lamar River are a bit high but clear. The lower end of Soda Butte will be the most crowded. A bit high will be a good situation in all waters considering the hot weather predicted for the coming week. Avoid fishing the Firehole below Old Faithful to give the already heat stressed fish a break.
Summer time warm-up has begun, but will really get going with the predicted heat coming next week. This means fishing early and late in the day just about anywhere is most productive. Growing aquatic vegetation makes dry fly and indicator fishing the most practical methods. Speckled dun life cycle patterns, deep, slowly trolled streamers (Type 2 or intermediate lines) , and midge pupa under an indicator and at the taking depth are best bets for action during these times. We have not received much specific information on regional still waters. Sand Creek Ponds are now open for fishing from non-motorized boats. Plenty of fish are being caught, but not many are trophy size.
Big bugs are up into Swan Valley meaning plenty of boats there, but PMD life cycle and sally patterns do best in riffles anywhere therefore offering some walk in wade fishing. Before riffle fishing becomes active try rubber legs or even a “Duracel ” jig dropper under your favorite Chernobyl variation. Flow out of Palisades Dam was dropped a few 100 cfs’s. This small of a drop does not impact fishing.