Posted on August 18 2020
Fished the sulfur hatch up in Deposit this afternoon. It didn't start until after 12:30 (they have bumped up the release so it takes longer to warm the water up to the 50's). Bugs got going fairly well but so did the wind. The fish? They seemed tired of eating sulfurs, there were a few brief flurries of feeding but it was mostly quiet. I left to mow the grass just before two. When I left there were still a good number of sulfurs on the water. If anybody stayed late and got into fish or at least saw lots of fish up please let us know.
This isn't a Q and A day but Ed S asked about the duration of the sulfur hatch and it's pertinent to today's report. Sulfurs like about 52 degrees water temp to hatch. When we get a reservoir spill in the summer the water temp goes way up and the bugs sometimes blow out. Same thing happens if we get a lot of warm rain that raises the water temps. The sulfur hatch below Oquaga seems to me to have been diminished by the recent rains to the point where most fish aren't feeding on top. Above Oquaga there are still bugs but the fish have become more reluctant to rise and fussier about what they eat.
If the releases are increased as they have been this week, more cold water enters the river and it takes longe.r to warm it up and the hatches are later. As August goes on. the sun is lower in the sky and less effective at warming the water. This also causes the hatches to be later (or in the evening, to end earlier). As the cold water beneath the thermocline is depleted (which is starting to happen now) the water warms and the hatch again blows out.
In answer to Ed S's question - It's way to complicated for me or anyone else to figure out. Have seen them gone by the first of July and have seen them hatch into September. Right now they are in decline below Oquaga and the hatches are changing their start time, duration and intensity above Oquaga. Also I might add. the fish have become so hard for me to catch that it's no longer fun.
Tonight I tried two spots, one in the WB that had fish feeding on iso nymphs (look for the splashy rises). Saw duns float long distances unmolested. Departed the WB at seven with a few sulfurs starting to hatch and headed down to the BR where I saw one iso, a handful of white flies and not a single rising fish. Did get two nice fish to eat blind casts but right now the Sulfur Zone appears to still be the place to go.