fly fishing small streams
Fly Fishing Techniques, How To Fly Fish

Reading the Water – Prime Trout Lies

In April, I discussed fishing during a hatch (Fly Presentation – Fishing a Hatch). For all but winter steelheaders, a unique group of trout fishers who mix cold and pain with relentless casting to catch their quarry, fishing for rising trout during a hatch of aquatic bugs is sheer nirvana for fly fishers. Unfortunately, a hatch is present only a small minority of the time. The remainder of the time, there is no hatch, but trout need to continue to feed. Most often they are feeding subsurface, but may be enticed to rise to attractor flies or terrestrials.

Consequently, in the absence of a hatch and rising trout, fly fishers often “fish the water”. That is, they throw their flies into the stream in hopes of attracting a hungry trout. However, trout are not uniformly distributed in a stream. They hold in specific areas, leaving most of a stream virtually barren of trout. If a fly fisher learns to recognize the areas where trout hold or lie when not actively feeding on the surface, and concentrates on fishing those areas, the likelihood of catching trout will increase exponentially. Searching the water for these holding areas is commonly referred to as “reading the water”. In this article, “Reading the Water- Prime Trout Lies”, I will discuss the elements of lies, how to recognize them, and how to fish them.

Elements of Lies

Trout have only a few basic requirements for survival. They need cool, well oxygenated water, protection or cover from predators, readily available food, and a break from the force of a stream’s current. A lie or holding area that offers all of these elements is generally referred to as a “prime lie”.

Other potential holding areas lack one or more of these elements, and are referred to as secondary lies. The most recognized secondary lies are “feeding lies” and “holding lies”. Feeding lies offer ready food and good water, but lack cover, while holding lies offer cover and good water, but lack ready food. Both must  provide a break from the current.

Trout move about among these different lies, but are most consistently found in prime lies.  In addition, the largest or dominant trout will be found in the prime lies. Therefore, reading the water, recognizing the prime lies, and fishing them properly, not only increases the likelihood of catching trout, but of catching big trout.

Small Freestone Streams

Small streams are the best classrooms for learning to read the water. Because of their small size, it is easier to explore their waters, and observe structures that slow or redirect the current. Streamside  structures, such as overhanging trees and grasses that provide cover, are easily observed as well. So, let’s begin with a look at a headwater mountain stream.

Mountain streams have a steep gradient and are often literally a series of plunge pools. The waterfalls and rapids put oxygen into the water, and scour out pools of varying size. Longer pools have deep, quiet water at their heads. Their rocky sides provide a break from the force of the current, allowing fish to hold with a minimum expenditure of energy. These streams are found at higher altitudes, and typically have thick, streamside foliage, which provides shade during the hot summer months. For these reasons, they remain cool all year long.

The riparian foliage also provides excellent cover from predators, including fly fishers. Thus their pools have all the elements of a prime lie. Below is a picture of  a typical, small mountain stream.

mountain trout stream
small mountain trout stream

Several plunge pools can be seen in the background, and a large pool or run is present in the foreground. Let’s analyze the large run. Most of the water is shallow, with a glassy-smooth surface. Due to its lack of cover, trout will not usually be present in this part of the run. If a hatch were to occur, some fish might move to the water just ahead of the two large rocks at the tail of the run (center foreground), which break the current and provide a bit of cover. Otherwise, the fish will remain in the small amount of prime water, at the head of the run. The water there is deeper, and there is a bit of surface chop, providing further cover. This small run has all the elements of a prime lie- cool oxygenated water, cover, and a current to carry food to the fish.

A fly fisher should approach this  from downstream. The quiet, non-prime water should be searched so as to avoid startling any unwary fish. If none are present, as is usually the case, the focus should be the small area of  prime water. The prime position from which to fish it would be just below the two large rocks at the tail. They will conceal a crouching fly fisher. And from that position, the fly rod will reach into the quiet water, and avoid “dragging” of the proffered fly.

Below is another picture of a small-stream run providing a prime lie. The run begins upstream of the large rock, and runs along the edge of the rock and under it as well. The rock offers protection from predators, and a foam line passes the edge of the rock. Bugs caught in the stream’s flow will be in the foam line.

If fishing a dry fly, it would best be fished by throwing a curve cast just upstream of the rock. The fly should be drifted downstream in the foam line, along the edge of the rock. If fishing a nymph, the cast should begin several feet farther upstream, allowing time for the fly to sink nearly to the bottom of the water column, before drifting downstream. I would fish the foam line, as with the dry fly, but then I would fish under the rock as well. The largest fish are most likely holding under the rock.

mountain trout stream
Prime trout lie in a mountain stream.

Next is a picture of a larger stream, the Firehole River in Yellowstone National Park. All the elements seen in the two mountain streams are present. There is a rock ledge crossing the entire stream, producing a modest waterfall. Quiet water is present just below the fall. Then the stream narrows, with a long, deep, run along the far bank. There is an obvious  foam line on the surface of the run, marking where food would be carried.  Good fish are likely to be found anywhere along the foam line, and along the edge of the quiet water immediately below the falls. The large quiet section is unlikely to hold fish, due to a lack of both cover and food.

Yellowstone National Park, middle geyser basin
The Firehole River in the lower geyser basin.

Another type of sheltering lie can be created by trees that have fallen into a stream. In the picture below, the dark water in the upper third of the picture is deep, and is running left to right. There is a foam line on the deep water, again indicating where food will be delivered. Trees have fallen into the stream from both banks, and extend into the deep run. All elements of a prime lie are again present. The entire foam line should be fished, with special attention given to the water near the tips of the logs, both upstream and downstream of them. This is especially attractive water for brown trout.

trout stream
Firehole River with underwater structure.

Spring Creeks

Now let’s consider spring creeks. The next picture illustrates a group of prime lies in a small spring creek. There are several midstream rocks and a log, which is lodged against the large rock in the middle. These structures provide a break in the water flow, and a rapid which engulfs oxygen. There is additional cover under the log as it nears the bank.

This picture reveals three prime lies to fish. The first is just upstream of the large midstream rock. The second is in the foreground, where the water passes the edge of the large rock, and there is a subsurface rock. The third is on the far side of the stream, immediately downstream of the log, where a small wedge-shaped piece of quiet water extends from the log to a foam line. These are great lies for brown trout. If rainbow trout were present, they would more likely be in the faster, choppy water downstream of the rocks and log. Each area should be carefully fished. Because of the small size of this stream and its clear water, it would best be fished starting downstream and working upstream.

spring creek with a prime trout lie
Prime trout lies in a small spring creek.

Spring creeks and other streams with muddy bottoms offer another type of prime lie which is created by their aquatic vegetation. In the picture below, the stream is flowing right to left. Thick vegetation is present, and leans downstream to the left, due to the current. The vegetation provides an overhead dome for cover, and also slows the water flow. Trout will typically lie in any break in the vegetation, such as the wedges of clear water seen in the left and center portions of the picture. If startled by predators, they simply glide under the overhanging vegetation. The vegetation makes it nearly impossible to fish deep nymphs, as they will get caught on the plants. Such lies are best approached from downstream, and fished with dry flies and/or lightly weighted nymphs that will stay in the film, that is, in the upper few inches of water.

prime lie for trout
Spring creek vegetation, creating a prime trout lie.

Moving to Large Freestone Streams

Larger freestone streams will often carve out yet another type of prime lie. The force of a stream’s current as it passes about the outside portion of a bend may erode the soil, leaving what is referred to as an “undercut bank”. As the picture below illustrates, such undercuts provide shade, overhead cover, and a ready supply of food, as indicated by the foamline along the bank. Whether fishing a dry fly or a wet fly, undercuts are best fished tight to the bank, following the foam lines. In summer, these are good lies to fish terrestrials, as they will often fall out of the overhanging grass and alight upon the water, where they get trapped in the film. Both cutthroat and brown trout love undercuts.

a prime trout lie, undercut bank
An undercut stream bank, offering cover and ready food.

Pictured below is a prime lie that anglers often overlook, an edge of rapid transition from shallow to deep water. This can be identified as a change in water color, from light to dark. Such edges can be found in both stillwaters and in streams. Foodstuffs reside in the shallow water, but trout will venture there only in low light conditions. During normal or bright light conditions, they will hang in the deep water at the edge, where they feel safe, waiting for bugs or minnows to wander over the edge. Whether fishing wet or dry flies, these edges are best fished by placing the fly in the shallow water, and letting the current carry it over the edge into the deeper water.

prime lie
A prime lie, created by an “edge.”

Now that I’ve illustrated the characteristics of prime lies in small streams, let’s take a look at a large river, the Madison River in Montana. Many fly fishers are overwhelmed when they first encounter such a large expanse of water, and either don’t give it a go, or simply pound the banks from a drift boat. But much better fishing can be had if the fly fisher breaks down the water mentally into small sections that resemble what they are used to seeing and fishing in smaller streams.

In the picture below, the stream flows left to right. The large boulder creates small areas of quiet water upstream, to the left and right, and a large area of quiet water downstream of it. Trout will lie in front of the boulder, and along the edges of the quiet and fast water behind it. This prime lie should be fished by placing a fly, wet or dry, upstream of the boulder, and letting it slide around the boulder and along the downstream edges of fast and quiet water. The largest trout will usually hold close to the rock, along the downstream edges.

Madison river
Midstream rock, producing a prime trout lie.

Next let’s look at the full expanse of the river, shown below. There are a number of easily seen, quiet, smooth areas. Each resemble the pools and runs shown earlier in the small mountain streams. Some, like the previous picture, are created by obvious boulders protruding above the water, while others are created by smaller, subsurface rocks. In both instances, these quiet areas indicate the presence of prime lies, and like the small mountain stream runs, are best fished along the edges of the fast and quiet water. There are enough prime lies seen here to occupy a wading fly fisher for an hour or two, and will be much more completely fished by wading than by simply gliding past in a drift boat.

trout stream
Madison River.

So next time you are out fishing, take the time to read the water, identify the prime lies, and spend your time fishing them. By doing so, you will markedly increase your chances of putting trout into your net.

I will discuss the other, secondary lies, in a future article.

Written by Al Simpson, August, 2015.                                                    Edited November, 2016.




10 thoughts on “Reading the Water – Prime Trout Lies

  1. It’s perfect time to make some plans for the future and it’s time to be happy.
    I have read this post and if I could I desire to
    suggest you some interesting things or tips. Perhaps you could write next articles referring to this article.

    I want to read even more things about it!

    My web blog; vpn coupon 2024

  2. What’s Going down i’m new to this, I stumbled upon this I’ve discovered It positively helpful and it has helped me
    out loads. I am hoping to give a contribution & aid other users like its helped me.
    Great job.

    my website :: vpn special

  3. Greetings, There’s no doubt that your site might be having
    browser compatibility issues. Whenever I look at your blog in Safari, it looks fine however, if opening in IE, it has some overlapping issues.
    I simply wanted to provide you with a quick
    heads up! Apart from that, fantastic website!

    My web-site: vpn 2024

Leave a Reply

Your email address will not be published. Required fields are marked *