Mid summer conditions are thankfully a thing of the past, now that we have had a real weather pattern change. River temps have dropped into the 50's and low 60's in the afternoon on a warmer day. I've still been assessing the status of our wild trout on our mid and large rivers after what was the hottest summer on record. I can say, that these wild fish have really adapted to warm water temps that generally are lethal to trout and have learned where to go to survive. Some rivers or stretches seem to have weathered the summer just fine, while others maybe not as well. I got out on the lower end of one of our big rivers and got some wild rainbows. I was concerned that there would be none left down that low. I definitely don't think all of the fish made through the summer it but thankfully some did in our warmest biggest rivers. I also don't think the fish have spread back out completely from their summer thermal refuges they migrate to, though I'm sure they will continue to do so. I'd say cover some water when you are out to find the fish and please take care to handle them respectfully.
Productive trout flies will begin getting smaller as most of the big bugs are finishing up their hatches, though you'll be able to get fish to eat bigger flies throughout the fall. I like to fish a larger 14 or 16 and then a size 18-20 mayfly nymph like a PT or red copper john. If you see fish rising on a slow flat or pool then throw a small size 18-20 BWO emerger. That is usually my first choice in this situation. The ISO hatch is about done, and unfortunately we didn't get to fish my favorite hatch of the year thanks to the hot water, but you'll still get fish to eat a size 14-16 ISO nymph either dead drifted or swung and stripped back to you.
As we get cooler weather and water temps, cold fronts will have an increasingly negative impact on the fishing. I've found over the years that the day after a front moves through leaving a sunny, cold, windy day with the wind coming from the north or northwest, the fishing can be very slow. I fished those exact conditions Saturday and things were definitely slow. Andy ran a trip that morning as well and the clients had a slow day as I did. We got fish to eat but most fish were not interested. The good news is that after things calm down, think sunday and today, the fishing is generally pretty good. Mornings, especially early mornings, have also been slower since it cooled down and as the water warms up so has the fishing. Just keep this stuff in mind when you are heading out to the river.
Lake run salmon will be starting the show up especially with any good pushes of rain. Along with those salmon will be a few browns and steelhead. It looks like we have another good shot of rain coming tomorrow so the lake tribs will likely get some big fresh lake fish. I like traditional streamers for those salmon like a black ghost. The longer they are in the river the less likely they will be to grab a streamer so nymphing will be more productive. I like mayfly and and caddisfly nymphs from size 14 to 18. Please let me know if you want to get out after some big lake fish!