Once again the South Fork flow graph for this week looks like a step function. Flow out of Palisades Reservoir was reduced yesterday to 5600 cfs ( now 6400 cfs at Heise, 3870 cfs at Lorenzo) from around 9000 cfs with several smaller drops throughout this week. Flow at this level will open up a lot more wading opportunities but make boating a bit tougher. Next week looks stormy, so look for continued good BWO and mahogany activity.
The current cool weather means the Firehole River is worth fishing again. BWO life cycle and white miller caddis patterns offer good ways to obtain action. So do soft hackle patterns. Be ready for stormy conditions! Look for early in the day trico activity on most streams. Terrestrial insect patterns will continue to work on all streams until a killing frost arrives. Most crowded streams include the Lamar in roadside meadows, Soda Butte Creek, Slough Creek’s lowest meadow (pressure on upper two meadows is thinning), Firehole River, Madison River, and lower Gibbon River on which the upper section is closed due to ongoing native salmonid restoration project.
No drop in flow here but mayfly activity on the lower river is similar (good) to that of the South Fork. Tiny BWOs (pseudocloeon edmunsi) are coming out on the lower river in numbers good enough to interest trout into near surface feeding. That means presenting very small (#18-22) life cycle patterns. Good luck if you tie into a trophy individual using one of these patterns!
Over the last two days flow out of Palisades Dam has been dropped sequentially to the current 7900 cfs. (now 4900 cfs at Lorenzo). This will not impact the BWO-mahogany dun activity. The currently cool weather is just the ticket to keep this activity going, but will slow hopper and other terrestrial insects fish like down to a crawl (literally!). Now that irrigation season is ending, look for more drops coming in flow out of Palisades Dam.
The predicted change in weather to stormier conditions this coming week is sure to bring on the late season BWO and mahogany dun mayfly activity. Consider stocking up on life cycle patterns for these two insects as they will help continue the great top water fishing we have had this year on the river.
Flying ants have arrived along the upper river, so add these to the grasshopper abundance, and terrestrial insect patterns of these should accompany your visit to this part of the river. Mayflies activity is reduced to a spotty trico emergence with some speckled duns thrown in. Caddis are still active here, but seem to be less in favor than especially ants according to resident trout (and whitefish). As always occurs this time of year, extensive weed beds put some limits on wet fly fishing and make escape havens for large hooked trout (and whitefish).
Water flow and temperature remain constant (around 9800 cfs at Irwin, 10200 cfs at Heise, 5100 cfs at Lorenzo) and mayfly hatches seem to be holding up. If you want to encounter fish looking for mutant golden stoneflies, best to be on the river at first light. Thundershowers and cooler weather are predicted for later this week. Hopefully this will help bring on the September BWO and mahogany dun activities because the current pink albert activity will begin to decrease with the onset of cooler weather.