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Fishing Technical Tailwaters: A Play Book

Published: 30th November 2020 | Author: James Garrettson

I love fishing technical tailwaters. Before the San Juan River was closed due to COVID-19, I managed to get out on the water for a day of fishing with my friend and fellow San Juan River guide, Doug Walker. We had a great day fishing, making fun of each other for missing hooksets, and talking technical trout fishing. With winter at our doorstep and tailwaters providing year round fishing opportunities for most trout anglers in the country, I hope these tips will put a few extra fish in your net this coming winter. 

Doug with a San Juan Trophy.

Think Trout First

What is trout first? Trout first is thinking about a trout’s biological proclivities before you even begin to rig. Tailwaters get a reputation for being hard to fish, but if you think about how trout react to things like temperature, bug activity, and angler pressure it should ease your next day on the water. In fact, when fishing technical tailwaters, the top two things I consider are temperature and angler pressure. 


While fishing in the winter the difference between a few degrees can mean active or sluggish fish. Also, weather trends that positively impact insects will generally make for better trout fishing. Low pressure systems tend to be a good bet for that.

Trout are cold blooded. When the water is colder their metabolic rate slows. You will find them deeper in the water column in their “winter lies”. These lies are generally the slower, deeper runs. O the other hand, as the temperature rises, you will find them in increasingly faster water. With that said, this is relative to each fishery. Some rivers are much slower in character overall, so consider this in the context of the rivers you fish.

Always check the temperature to make your best judgment where the fish will be when fishing technical tailwaters.

These temperature changes effect the bug life as well. So, when temperatures rise and bugs become more active, the fish often follow suit. If a thick midge or BWO hatch pops off, you can find trout throughout the water column and even pushing up into riffles which are connected to winter lies

Considering water temperature before you begin fishing can help you locate the most productive water and also make your rigging decisions clearer. Will they be deep? Will they be chasing bugs higher in the water column? Your rigging decisions depend on figuring this out.

Dave focuses while keeping an eye out for surface midge eaters.


Tailwaters and heavy angling pressure go together like politics and Thanksgiving. Much like you don’t want to hear your Aunt April talk about shape shifting reptilians from the Draco constellation running the government, you also don’t want to show up to a crowded river. But hey, it happens. Most importantly, what do you do about it and how does it impact the trout? 

While really pressured trout seem to lose all fear of humans, they make up for it in other areas. Tailwater fish become increasingly drift sensitive, and in some cases will have very specific feeding windows. This became apparent to me this past summer when I fished a famous tailwater in the A.M. with mixed success; I went back at night to find fish gorging. They knew there would be less people around.

Doug watching the indicator. These heavily pressured midge eaters are well known for their light takes.

Because tailwaters can have such a large biomass of small insects, the trout that live there become size sensitive as well during peak hatch times. While the opposite can also hold true, I generally subscribe to the mantra that pressured fish are more likely to eat smaller bugs. When fishing smaller bugs you’ll also want to fish lighter tippet. A good rule is to divide your hook size by 3. I fish a lot of 6x and even 7x when I’m throwing light midge rigs. I don’t fish light tippet because the fish “can’t see it”, I fish light tippet because it gives you a better drift. In pressured tailwaters, drifts matter. If it looks unnatural, they won’t touch it.

Other Considerations 

While not all tailwaters are created equal, they do all generally have a huge biomass of insects. The consistent year-round temperature combined with good year-round flow creates a trout paradise. This is why some tailwaters like the San Juan can have trout populations that are estimated around 12k fish a mile. Yes, you read that correctly. Because there is an ever-abundant source of food coming right to the trouts’ faces, it means they don’t have to move very far to eat.

On many tailwaters, trout will get locked into a band of the water column and stay there for long periods of time. Many times “matching the column” is the most important part of the tailwater equation. So, you’ve got to learn how to find what column the trout are feeding in.

The action suddenly slowed, but after a quick depth and weight adjustment, Doug was right back into fish.

Our Day on the Water

Doug and I met up at the boat ramp at 9am. This was early November in Northern New Mexico and we wanted to let the water bump a couple degrees before we began our day. 

The water was still a little cold and the midges hadn’t really started coming off yet. The fish in the Juan are tied to the midge cycle. Blue winged olives are also a major hatch to consider daily. As a result, we started with medium weight and went deep to begin. The typical San Juan rig is a tapered 5x leader with about 18-ish inches of 6x fluorocarbon blood knotted in. Above the knot is where you crimp your split shot. You tie your first fly to the 6x piece you spliced in and then usually go another 18-ish inches to your second fly. I like to rig eye to eye as it gives you more hook gap because the knot doesn’t block it, especially on the really small stuff. 

Doug rigging up a typical San Juan setup. Note the spacing between the shot and the flies.

The morning was filled with laughs and fish as Doug and I both fished the lower parts of the water column. As the day warmed the rigs got lighter and lighter until we were fishing the upper column for trout eating the emerging mayflies and pupating midges. Doug pinned a few up on some dries in the afternoon. I even got out the euro stick and pinned a few. We pretty much kept the same couple bugs on all day with the weight and the distance from the split shot changing frequently from spot to spot. 

Interested in learning more about technical fishing? Check out James’ recent article about dry fly tactics.

Putting it all Together 

Don’t let fishing technical tailwaters scare you this winter. Just remember that trout are animals with pea sized brains. If you can think trout first and match the general band of the water column they’re feeding in, you’re going to do great. When in doubt, drop your fly sizes. However, I would recommend playing with your weight and indicator-depth-to-weight ratio before getting crazy on the fly sizes. More often than not, it’s a good presentation that gets the job done. It’s better to fish the “wrong” bugs in the right way.

2020 has been absolute insanity; spending a day on a tailwater this winter may help you forget—for at least a little bit. Happy fishing. 

To learn more about James or Doug check out their respective guide services or and

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