Reading The Water, or Where The Trout Are
When flyfishers refer to "reading the water", they mean finding those
places in the stream where fish are likely to be. There are two separate
steps to finding trout. The first is to examine the types of water you will
be fishing and the second is to analyze the needs of a trout. The
combination results in the concept of fishing lies, or the holding areas of
trout. This is the traditional concept of reading the water.
I want you to take your observations several steps further by using this
knowledge to help you spot the trout. I then want you to learn what fish
foods occur in the various water types I will describe and to correlate
this with any feeding behavior you see. We can use this knowledge to choose
our flies and our presentation so that we fish these flies in a realistic
manner. I call this method a systematic approach to flyfishing, and it is
explained in greater detail in the other FAQs. (Put links to Dry Fly and
Nymphing FAQs here)
Without a systematic approach to flyfishing, it is difficult to fish an
unfamiliar piece of water. What would you do when faced with a large
western river like the Madison or Yellowstone? Where would you begin?
I begin by breaking the river down into its different water types. In a
large river, there there may be several types of water next to each other,
so break large rivers down into manageable sections.
There are five major types of water in any river system. These types of
water are the result of three physical characteristics of the river system.
They are the gradient of the river bed which determines how fast the water
flows, the bottom structure which determines how turbulent the flow will
be, and the depth of the water (inversly related to the width of the river)
which determines whether the turbulence reaches the surface.
The combinations of factors leads to rapids, riffles, runs, pools and
flats. In general this progression is from the steeper gradients with
faster and narrower flows to the flatter gradients with slower and wider
flows. The steeper gradients cause faster and generally deeper water flows.
These faster flows can suspend more solid particles and cut a narrower
channel into the underlying bedrock. As the gradient lessens, the stream
tends to gradually widen, meander, and flows more slowly.
Rapids are the fastest and roughest water in the river. Here you will find
the largest boulders, since these are the only structures which can remain
stationary in the face of the fast water. These boulders and the fast water
combine to form standing waves in the water column which is typical of
rapids. The fastest rapids are generally unfishable but the gentler areas
can provide good pocket water. Look for quiet areas on the inside of
curves, near the banks or behind the boulders.
Riffles are the food factories of a stream. They are the result of moderate
to shallow depths, 3-4 ft. maximum, with moderate flows over a cobblely
bottom. This results in small irregular waves on the surface, good
oxygenation, and light penetration to the stream bottom. The light
penetration allows for growth of vegetation and small phytoplankton which
form the basis of the aquatic food chain. The cobblely stream bed increases
the surface area upon which the vegetation and secondary aquatic insects
can live. This combination results in riffle water being a prime area for
Runs are deeper than riffles and have a smoother surface to the flowing
water. The flow rate tends to be less than a riffle and much less than a
rapid. This is the result of the greater depth and the smoother bottom.
They also support aquatic insect life but usually less than a riffle.
Pools are the deep water areas of a river. Because of their depth, the
flows can be quite slow in the larger pools. The hallmark of a pool, is
it's depth, usually greater than 6 feet and too deep to see the bottom. The
water depth limits light penetration and there will be less insect life
than in riffles or runs. Because of their great depth, pools tend to hold
the largest trout which generally feed on baitfish.
Flats are the stillwater areas of a stream. They are often found in a wider
section of the river off the main channel. Because flats are defined by the
glasslike nature of their surface, they have a smooth bottom and most have
only a slight gradient. They tend to be less than 3 feet or less in depth.
Fish usually venture into the flats only to feed, and they generally are
As I said above, a larger river may have a mixture of the water types in
one segment of the river. A riffle and run may be side by side or theyre
may be a run on one side and a pool on the other. You must treat each type
of water differently even if they are side by side.
THE BIOLOGICAL NEEDS OF A TROUT:
After the biological requirements of proper water temperature and dissolved
oxygen, the needs of a trout are safety, shelter, food, and reproduction. I
have listed the primary needs in descending importance.
Safety is the primary concern of a trout. This usually means overhead cover
by either a physical structure, water depth or rough water. Second is
shelter by which I mean shelter from the current flow so that the fish can
maintain his position with minimal effort. A trout will always seek these
two factors first.
Third is access to food and fourth is reproduction. By reproduction, I mean
the need to spawn, which can temporarily overcome the other factors.
When we consider the water types and the needs of a trout we can develop
the concept of fishing lies.
Fishing lies are locations that describe where the fish live. There are
three main types of "lies", or places that may hold fish. They are the
sheltering lie, the feeding lie, and the prime lie.
The sheltering lie provides both safety and shelter, the two most important
factors for a resting fish. It is most often in deep water and acts as a
fish sanctuary. This is usually the deepest part of the water in the
section you are fishing or it is the area which provides the greatest
safety, such a brush pile or sunken tree. It is the location a fish will
try to reach once it is hooked.
The feeding lie is where the fish come to feed, but it offers no safety or
shelter to the trout. Therefore, these areas will be sterile in nonhatch
situations. Flats would be an example of a feeding lie. Shallow water at
the head of a pool or riffle are other examples of feeding lies. Ignore
these areas during nonhatch periods.
This leaves the prime lies. Prime lies are areas which are both feeding and
sheltering lies. They offer simultaneous access to food, safety and
shelter. Examples are undercut banks, low overhanging willow branches, or
beneath a log in the water. There must be both overhead cover which gives
the fish protection from predators, shelter from the main current, and a
location near a current seam which will funnel in the food.
WHERE ARE THE PRIME LIES:
Look for areas where water flows next to or against a stationary object.
This is necessary to shelter the trout from the current. In a stream, water
which is closest to the stream bank and bottom have the slowest flows. A
slight depression or a cantaloupe sized rock is all that is necessary to
provide shelter from the current. The fish can be in front of, to the
sides, or in back of such objects. If you can find these areas of shelter
next to a current seam, they can be prime lies.
A large boulder or rock in the middle of the stream can be a prime lie,
since the water depth and turbulence will provide saftey and shelter, and
the rock itself will deflect the current and cause a seam. Any such boulder
is a prime lie.
The best areas to fish are these prime lies since there will usually be
fish in that location. To find a prime lie we look for the combination of
overhead cover (safety), solid objects (shelter), and a passing current
seam to bring in the food.
In the rapids we refer to these lies as pocket water. These are the
backwash areas behind , to the side or just in front of the boulders. In
the fast rapids you will only be able to fish the backside of the boulders
but in lesser flows you can also fish the hydraulic cushions to the sides
and in front of the boulder. You want to place your fly on the inside
(toward the quiet water) portion of the seam
In the riffles, almost all the water is a prime lie. Here the cover is not
provided by depth but by the surface turbulence which serves to hide the
fish. The many underwater rocks provide the shelter. Fish the entire riffle
systematically as described in the FAQ on Fishing The Dry Fly.
Runs usually occur at the tail out of a riffle. The top of a run is often a
prime lie or feeding lie and can be fished during a hatch just as the
riffle. During the non hatch periods try fishing a nymph from below, tossed
up into the riffle and washed down into the run. When approaching from
above, fish a streamer downstream into the head of the run.
Pools are the sanctuary for big trout. Although there can be surface
activity during major hatches, pools are best fished with streamer type
patterns such as a wooly bugger. If night fishing is allowed in your area,
pools can offer up large trout on large surface or subsurface patterns such
as a muddler minnow or mouse pattern. During hatches, the best action will
be at the head of the pool where the largest trout will station themselves
to intercept the floating drys.
Flats unless they are deep will hold trout only during the hatch. You will
need to fish these hatches much as you would still waters or spring creeks
with long tippets and a stealthy presentation. Because of the glasslike
quality of the water surface and the limited water depth, the trout will be
extremely wary and only the best fishers will generally be successful in
fishing the flats.
MEANDERS, BANKS AND UNDERCUT BANKS:
As a river matures it will form meanders or curves. As the water is forced
around the outside curve it will cut a channel under the outside bank.
These are called undercut banks and are a favorite prime lie especially for
brown trout. The trout is protected by the overhead bank and the current
flow next to the bank is slow. The current as it rounds the bend will bring
Any bank next to deep water provides a sheltering lie or a prime lie. Even
if the water is not deep, if it is protected by overhanging vegetation or
bushes, it will be a prime lie. Look for these areas especially in riffles
and runs. If there are considerable overhead bushes for cover, even the
bank areas in flats or other shallow water areas will provide sheltering
Eddy currents are reversed currents or backwashes. They are usually caused
by an object projecting into the main current flow from the side. An
example would be a tree that has fallen crosswise into the river. Behind
the tree, there will be a whirlpool effect where there will be currents
which rotate with some flowing upstream or across stream. Since the trout
will orient themselves to the current flow, the trout can be facing
downstream or even sideways in these eddies. When you see a fish rise in
such a backwash, look carefully at how the water is swirling so that you
present the fly so that the eddy current takes the fly to the fish.
BECOME A HUNTER:
It always seemed strange to me that most fishermen simply walk into a river
and start fishing when they would never think of doing a similar thing if
they were hunting. You don't see a hunter fire blindly into the woods where
he *thinks* his game is hiding, and then walk into the woods to see if he
hit anything. Yet, that is exactly what you are doing, if you simply walk
into the water without looking for your prey. You must think like a hunter
because that is really what we are doing. We are hunting fish.
Take a lesson from the osprey and the blue heron, two of nature's finest
fishers. They spend more time watching and looking than fishing. Once you
have read the water and know where the trout should be, look for them
there. If you are a dry fly fisherman, look for the subtle signs of a
feeding trout. A small dimple just behind a log across the stream may be
your only clue. Before you step into the water look at all the prime lies
in your area.
Then you want to consciously look into and through the water. Just as the
deer hunter learns to spot his prey by seeing only a part of it's body, we
as fishers must learn to recognize fish by seeing only a part of its shape.
One key is to look for motion. A fish never stays still so look for the
telltale side to side motion of its body or tail. Look for it's bullet
shape or its shadow against the stream bottom. Ususally the back of a trout
will be the darker shade of the stream bottom but the side may have a
lighter shade. Rainbow trout will often give themselves away this way. Look
for this subtle change in color as the fish turns sideways when feeding on
the bottom. It becomes almost a gestalt as the trout appears before your
The mouth of a trout is usually white which you will see appear and
disappear as the fish feeds. Look for it since it is a sure sign of a trout
feeding underwater. This is often accompanies by a sideways turn of the
body. A writer has called it looking for the wink under water, like an eye
opening and closing.
As I said in the Dry Fly FAQ, your chances of catching a trout goes up
tremendously if you spot him before he spots you. So give yourself every
opportunity to be succesful by carefully reading *through* the water.
READ THE FOOD:
In addition to reading the water it is possible to read the the trout's
food. By this I mean that certain water types will contain typical aquatic
insects. Those of you who have read my other FAQS, know that I am a
proponent of sampling nets. I find them invaluable in learning what foods
are available to the trout and therefore what flies to use. If you will use
them, you will also discover the types of aquatic food that are typically
found in the various lies.
Stoneflies, as their name suggest, typically live in the portions of the
streams with rocky bottoms. This usually means the faster flows needed to
keep the silt and sand off the bottoms. They are usually found in rapids
and riffles. They can also be found in some runs if the bottom if cobblely.
Since many stonesflies take several years to mature, they are available
year round to the trout.
Rapids and Riffles will also have an assortment of clinging and crawling
mayflies. Clingers have the flat bodies necessary to keep them plastered
against the rocks in the rapids and riffles. As the water slows in the
riffles, there will be more crawler mayflies. There will also usually be
some net building and cased caddises in the riffles. You can tell what form
the nymphes will take by the water type you are fishing.
As the flows get slower in the runs, the mayflies will change over to the
crawler types with the rounder more elongated bodies. The caddises will be
the the case builders. There may still be some stoneflies if the bottom is
rocky. If there is silt along the edges of the runs or on the inside curve,
look for a population of burrowing mayfly nymphs.
In the pools the main food source of the trout will be minnows and
sculpins. There may be leeches or crayfish and the other larger fish foods.
So you should switch over to the streamer/wooly bugger type of flies for
this type of water during nonhatch periods. However, if the pools have silt
on the bottom or along the sides, there may be a good population of the
burrowing mayflies. You can plan on good fishing during these hatches.
Remember that not all of the trout food comes from the water. When you see
prime lies near the banks or under the trees, don't forget the terrestrial
insects - ants, grasshoppers, jassids, and caterpillars.
Now correlate what you know about the available food types with any feeding
behavior you observe. Use all the information to select your fly and
Reading the water is a matter of recognizing the different types of water
in a trout stream and where the trout will generally be for each water
type. The trout will generally seek out its requirements in the order I
listed above. Find the prime lies (overhead cover, shelter from the
current, and a food source) and you will find the trout.
Then act like the hunter you are and try to spot the trout in those lies
before you start to fish. Use your knowledge of the water types, aquatic
foods, and any feeding behavior you observe to select your fly. Then vary
your presentation for the type of water and food you are fishing, so that
your fly and presentation look natural for that water type.
More complete information about this systematic approach to fly flyfishing
is given in The Dry Fly and Nymphing FAQs.
Copyright 1996 by Henry Kanemoto.
No reproduction, electronic or otherwise, is allowed without permission of