Gravity pulls it downstream. All of it. Every drop of water merging into a river, whether fallen directly from the clouds into a small brook, or bubbling from a spring seep on a large and open river, is under the consistent influence of a force none of us can see. But we all feel it. It’s predictable. Gravity holds few surprises. And though its mystery runs deep, we’ve each learned, from birth, to expect the unseen force holding our world together to keep doing just that — to keep all the parts and all the stuff stuck tight — trusting that the center will hold and things won’t fall apart. It’s consistent enough to be boring, really. But as an angler, the effects of gravity on flowing water is fascinating. And it’s fundamental. It’s the key to reading trout water.
Pulled along by gravity, water follows the path of least resistance downstream until it ends up in some ocean (usually). This is a fun concept to explain to my young boys, how the tiny brook in the backyard merges with Spring Creek in Bellefonte, into the next river, on down into the West Branch of the Susky, then the Susquehanna, and out to the Chesapeake Bay.
“Noooo waaaay!” Aiden says, when I show him this course on a map. He’s old enough to have gained some perspective on distance now. He knows how many hours it takes to travel halfway across the state to Grandpa’s house. And now, as we roll down the highway, he watches for drainage ditches and bridges large and small. “That water was in our backyard,” he says, as we cross a bridge on I-80. “That’s right, bud!” I tell him. “More or less,” I whisper under my breath.
If you’ve never thought about all this, or if you’re a new angler who didn’t grow up playing in a small runoff stream (building rock dams and intuitively learning hydraulic flows) then it’s probably time to consider what makes a river run downstream — because you can be sure that the trout know all about it.
I’ve studied a bunch of books about reading rivers, and Dave Hughes’ 2010 work, Reading Trout Water is my favorite. Hughes breaks down every nuance of moving water and how it relates to trout, in 312 pages of detail. I’m not foolish enough to attempt anything like that in this short tip of fifty. Instead, I’ll merely suggest that reading the water and finding willing trout starts with understanding how the river flows.
Water flows faster where the gradient is steeper. Sure, that’s easy to see when comparing a riffle with its neighboring pool, but it’s less obvious within that riffle. Finding the edge of a current break, or seeing a submerged log stuck in the riverbed, leads you to the places where trout live. We know that trout look for structure, but perhaps it’s more helpful to expect trout at certain features. (Words matter.)
The undercut bank is obvious, but the unseen, minor shelf, just eight feet long and ten inches deep, is harder to find. Gravity, though, gives it away. And learning to read trout water starts with identifying and understanding surface currents. When water flows faster and deeper into a pocket created by that ten-inch shelf, you can see its effect on the surface. And that’s the key.
Large, seemingly featureless waters are never truly that — every river has features to be found and surface currents that give away the structure of the streambed.
Learning to read water is easier on a small stream. Find a river with lots of rocks, wood, hard bends and gradient shifts. Notice what those features do to the flow, how the surface currents are affected along with the base current. Then take that knowledge over to the large “featureless” stretches of river, and it’ll be clearer to you where trout may live.
All of this is important because trout don’t hold in every water type. And wherever they’re holding they’re not always feeding. A certain percentage of the river is unproductive, and of course, that varies with different seasons and conditions.
Watch for the main flow. In every piece of water, determine the primary stem of current running downstream, then pick out the side flows. See how they have their own branches that diverge and later combine with each other. Find those points of diversion and conversion, and you’ll often find a trout or two as well.
Fly fishing, at it’s best, is about teaching yourself. Or really, it’s about giving yourself a chance to learn these things. Fill your head with ideas, and then go out to the river to explore them. Grow that knowledge into something you build upon, something that eventually feels familiar and natural.
Fish hard, friends.
Enjoy the day
T R O U T B I T T E N