How to Read a River for Trout Fishing: Mastering an Art

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River in British Columbia

Trout want three things in rivers: food, oxygen, and safety. Anywhere they can find all three is the perfect place for trout to sit. Whether it’s a pool or under a cut bank, trout want to exert as little energy as possible while having ample access to protection and food. 

A part of becoming a better angler is learning how to read water. Reading water is a mixture of science, assumption, and imagination. The better anglers understand where fish hold, the more trout you’ll catch. Trout aren’t overly challenging to find in a river, but catching them is a different challenge. 

Look for Slack Water 

When you get to the river, sit and observe it for a few minutes. Look for changes in current speed, cover, structure, and changes in depth. As you’re doing this, you’ll notice parts of the river that don’t appear to be moving as fast as other sections. 

A small section of water behind a rock, a pool, or up along the banks is the perfect place to start. Slack water almost looks like it’s not moving compared to the rest of the river. 


Trout love to sit in pools. Pools are deep sections of water that look like they have little to no current. On either side, you’ll find shallow water. Trout sit in pools because they provide protection, comfortable water temperatures, and easy places to sit. Rocks, logs, and other debris move into the bottoms of pools, providing plenty of protection from predators. 

Plus, food like insects, smaller fish, and crustaceans drift into these pools, making it easy for trout to eat them. 

Depending on the time of day and the trout’s aggression, they’ll feed in the front, middle, or back of pools. I always start by fishing the front of the pool. I’ll let my nymph or streamer drift from the riffles into the front edge of the pool. If I don’t get a hit or a flash, I’ll let it drift a few feet and strip it towards myself to see if trout want to chase it. 

If I get no action at the front, I’ll let my fly drift a little longer into the middle of the pool. Here, I’ll let it fall further in the water column. The pool’s center is usually the deepest, so your bait needs time to get to the bottom. 

If nothing happens in the middle, I’ll swing my fly toward the back of the pool. By swinging my fly across the back, the trout can make a last-second grab before it floats back into the shallow water. 

You’ll find pools in bends in the river, up along rock walls, and various other parts of the river. When in doubt, start fishing for trout in pools and then move to different sections if the pools aren’t producing fish. 


Pockets are sections of water right behind large rocks or logs where the water is slack. The current flows on either side of the rock or log, but it looks like it stops directly behind it. This small section of water is the perfect place for trout to hide. 

They can dart into the current on either side of the rock for food and return to the slow water after feeding.  

Pockets are some of my places in the river to fish. Many anglers pass by dozens of pockets to get to a pool or cut bank. A single pocket of slack water behind a rock can hold a few fish, so don’t pass on them. A properly drifting fly, bait, or lure will get a strike every time. 

Accomplishing a natural drift into a pocket isn’t always easy. The fast current on either side of the structure causes many lures, flies, and bait to look unnatural. 

Keep as much of your line out of the water as possible to accomplish the best drift. The less line in the water, the less chance of getting snagged. 

I’ll throw my fly 10-15 feet above the pocket and drift it on the side closest to me. As it drifts downstream, I’ll strip in any excess fly line and raise my rod tip. This helps the fly lead the way downstream and keeps me out of trouble. 

As soon as it nears the pocket, I’ll let it get sucked into the slower section and wait for a strike. 

If letting my fly enter the pocket isn’t working, I’ll keep my fly a foot or two away from it. I’ll keep it in the current alongside the pocket in case the trout want to swim into the current, grab it, and return to safety. 

Danny fly fishing in River on Vancouver Island
River on Vancouver Island

Cut Banks

Cut banks are sections of water along the edge of the river carved out by years of current. Banks made of dirt and sand are the perfect places to look. 

Just because the water looks like it runs along the edge doesn’t mean that’s all there is to it. Odds are, the underside of the bank stretches a few feet wider than it looks at the surface.

These carved-out sections have slow currents and perfect hiding places for giant trout.   Cut banks are where I catch my biggest fish. If I’m fishing a river I can wade in, I’ll head to the middle and face the cut bank. 

When fishing cut banks, you want to be as close to the bank as possible. You’ll be dealing with numerous currents, and they can ruin your drift. You want your fly to drift along the bank as slowly and naturally as possible. 

By standing close, you can control the drift far easier than you would if standing 25-30 feet away. I don’t want to make more mends in my fly line than necessary, and standing close prevents unnecessary and unnatural mends. 

Streamers and nymphs work extremely well for cut banks. The slow current will suck them under the bank for the waiting trout. Again, keep your rod tip high and let your fly and leader do the work. 

These cut banks may not look like much, but if you swim underwater, you’ll see all the fabulous hiding places for trout. Any bank with weeds and soil along it is a prime area to start. 

River in Wyoming
River in Wyoming


Eddies are some of the best places to find slack water. Eddies are bends in the rivers or wider sections of water that slow down and create hiding places for trout. 

When fishing bends in the river, you’ll notice a section with much slower water than the rest. Sometimes, this slow water is right along the bank. Other times, it’s closer to the opposite shore. 

Fish sit in these slow sections because they’re deep and function like pools. You may have to throw streamers or large nymphs into these sections and strip your flies to get a strike. The minimal current makes it challenging to create natural drifts. 

I’ll stand along the shore and fish the slack water closest to me. I’ll stand right before the bend in the river, cast my fly upstream, and let it drift into the slack water. As the fly swings, I almost always get strikes. Trout love a juicy-looking streamer drifting across their faces. 

Eddies provide great fishing at all times of the day. 

Find Changes in the Current 

When I stand on the edge of a river and look, I pick out all the different current speeds. It’s not uncommon for a 20-foot wide section of water to have four or five different current speeds. If I can’t find a great pool, pocket, cut bank, or eddie, I’ll focus on the different currents. 

I’ll find the slowest-moving water and start there. If the water is deeper in this slow section, I can assume the trout are sitting deep. A well-drifted nymph or streamer gets the trout’s attention at the bottom. 

I may have to wade into the river to get closer to this current because I don’t want the faster currents getting in my way. 

If I’m not getting strikes in the slowest current, I’ll move to the next slowest and work my way up to the fastest. I almost always try to fish deep unless I see fish rise at the surface. The deeper water is always going to stay the slowest. Trout don’t want to spend their days fighting current, but they want ample access to food. 

The Colorado River
The Colorado River

Look for Bubbles

Bubbles are always a good sign. Bubbles mean oxygen, and oxygen means food. You’ll find one long seam of bubbles after a waterfall, beyond a section of riffles/rapids, and near large sections of cover and structure. 

The more oxygen a fish has, the better. Fish your bait, lures, and flies along the bubble line. Fish sit in these areas all day long. Bubbles are a great place to start if you’ve never been to a river. Plus, if you’re fishing large rivers, you may not know the location of any structure or cover, so the bubbles act as the perfect place to begin the day. 

Look for Cover and Structure

Almost all freshwater fish prioritize cover and structure. Trout want places to hide in case a large predator appears. Cover and structure include boulders, fallen logs, aquatic vegetation, and other objects that block current and provide safety. 

If I’m new to a river, I always look for a partially submerged tree or large rock pile. I’ll start by fishing behind these in the pockets. 

Not all cover and structure is easy to see. If the water is clear, walk along the bank and look for larger rocks or trees hiding under the surface. Trout don’t always need massive boulders or logs. They’re happy to sit beside smaller objects if they provide protection.

No matter the time of year you’re targeting trout, they’ll always spend time near cover and structure.

Large River in British Columbia
Large River in British Columbia

Understand the Food Situation

Before you start fishing, do your best to determine what the fish are eating. Reading hatch charts is a great thing to do before leaving your house. You can find these online or call a local fly or bait shop. 

If you can’t find a hatch chart, study when you get to the river. Turning over rocks or logs in the water gives you a great look at all of the insects that hatch. Grab one and see if you can match it to a fly or lure in your box. 

Once you’ve studied the insects, identify any crustaceans or smaller fish the trout might eat. Any sign of minnows or crustaceans permits you to throw streamers, spinners, and live bait. 

I love taking 10-15 minutes to study the water and insects at the start of my fishing trip. I’ve learned many valuable lessons by watching trout feed and studying their food. Their habits change depending on the time of day and season. 

Be Careful With Your Approach

Too many anglers spoil a perfect pool or seam by making too much noise. Everything about your approach matters. Avoid splashing around, casting your shadow over the water, and making sudden movements. 

Depending on the water clarity and the spookiness of the fish, I have to get on my knees and make my way towards the water’s edge. Most of the time, however, I stand 10-15 feet away from the water and observe. The more time I spend observing, the more I learn. 


The more confident you get reading water, the better angler you become. It takes years and dozens of trips to the river to understand exactly what is happening below the surface. As you get more comfortable, you’ll notice that many things that happen in your home river also happen in other rivers. Look for slack water and protection. Also, pay attention to the bubbles and know what the fish want to eat.

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