I primarily fish the Brazos River outside my house. It is shallow water and cools off or heats up fairly quickly, depending on how much sunlight and wind it gets and the temperature of the air. Last week the fishing was good, the water was cool but not cold. Yesterday the water was cold, cold enough to hurt when I waded in.
Eventually I got kind of used to the cold water, I was bare legged of course. When the water gets cold enough that waders seem like a good idea, the fish pretty much quit biting anyway, so I don't use them here. Not only was the water cold, it was the clearest I've ever seen in this river - and this is a clear water river to begin with.
I don't know the words to describe this level of clarity. Invisible is pretty near what it is. But for the breeze rippling the surface you'd think there was no water there. I could see fish, I could see lots of fish, and they looked to be suspended in air below a slightly rippled layer of thin water above them and a layer or clean gravel below them. It is downright weird to see the water this clear.
The river is so low that it barely has any current, for all intents and purposes it is still water right now. The fish I saw were mostly being still until I disturbed them. Then they darted away, but not far away. I don't think they have the energy to go far right now. I would lay a fly down as softly as I could and the fish would take off, darting away from the fly, as though I was throwing cherry bombs at them. Extraordinarily spooky. There was no activity otherwise, no feeding actions anywhere. Generally there is a fish somewhere in the river that breaks the surface chasing something, but not yesterday.
I fished for an hour and a half without so much as a nibble, not even a fish casually following the fly in. And I was cold, what little wind there was came out of the north, and since I was standing waist deep in cold water wearing only shorts, a tee shirt, and a fishing vest - that little wind was a bit less than charming.
As I waded back out I saw a Needle Nose Gar lying on the bottom, half under a large rock, its nose and tail sticking out either side. It was right at my feet and not moving. I poked it with the end of my fly rod three times before it moved away, and then it moved away languidly.
Unless we have a week or longer hot spell that warms the river up, it looks like my warm water fishing season is at an end until next spring. With luck we'll have the usual spotty winter, with long warmish spells that do warm the water up enough to get the fish to bite a little bit. Hope so. Otherwise it will soon be time to try to catch the hatchery trout TPWD release each winter (they don't much cotton to flys, although I've seen people catching them easily on powerbait and spinning gear) and dreaming of next spring when I'll have a new float tube to try out.
I'll spend the winter restocking, I might even tie a few flys. I've been thinking about doing that again and winter seems like a good time to give it another go. That way I can make the kind of woolybuggers that work best here - and also make those hard to otherwise find bullyspiders that the bluegills love.
The river changes all the time, and this period of extremely clear water is unusual in my experience. I've see the river with black muck mud a foot thick all across the bottom for two or three years, it was like wading in a swamp. Bubbles that emitted foul gas would boil up with every step, moss was so thick you could barely wade through it. That was the other extreme I've seen. This clarity is a result of no rains in a long time that washed silt into the river and the dam letting out a good bit of water that flushed away any silt that was in it, and the very low levels with just about nothing for current that keep any sediment there is down on the bottom.
The clarity is gorgeous, makes for the prettiest river you ever saw - but it hampers fishing. If you can see the fish, they saw you a long time ago and got spooked. They are already spooked anyway by the clear water because they are exposed big time to the fish eating birds, of which there are thousands. I will enjoy the beauty of it while it lasts, but I won't lament it leaving when it goes. A bit of murk in the water is better for fishing.
The river changes all the time, hot to cold, clear to muddy, clean gravel bottom to muck on top of the gravel, fast current to slow current, trees move into places and hold fish then the trees go down the river, gravel bars come and go, holes fill up with gravel or empty out.
The river changes all the time, that is one of my favorite things about it.