Return to Mill Creek

Notes on stream ecology.

  • By: Maximilian Werner
Lacunae Image LR 2.jpg

I was fishing Mill Creek late in the afternoon and I saw a sleek rainbow nestled in the shadow of a fallen tree. I had just lost my last Elk-hair Caddis in the trees and was now drawing from my miscellaneous row of flies. On a trip to Christmas Tree Lake in eastern Arizona, I had bought a dozen blue damsels, which are a much anticipated food source for the Apache trout that inhabit the lake. That was nine years ago and I still had a couple of those flies, so I tied on one and studied the water. I was about six feet above the trout, but I was careful to keep a patch of wild mint between us at all times. I needed a little time to wiggle out some line before the current sucked away my fly, so I got down on one knee and cast the dry into the slow water just inches away from the current.

If a river rod is a means to an end, a stream rod is an end in itself. A rod guides and conveys the line, but on a small stream where casting may not be an option, these two functions must often be suspended. Instead of casting the fly, the rod extends the angler’s reach, like a long, thin arm. A small stream rod also relies heavily on the angler’s imagination (Metcalf showed me how to use the rod as a sling shot, a method that comes in very handy when the rod itself cannot be moved).

Thus, a few seconds after I wiggled out my line (an odd but illustrative verb), the current took the fly. When the damsel was about six inches above the trout, the trout wafted out from the shadow of the log, opened its mouth and waited for the damsel to float into it. Half above the water and half below, the trout’s mouth was round and a little bigger than a quarter. The sight of a trout opening its mouth to feed would seem as familiar as the sight of a trout swimming. I have seen thousands of trout swim, and yet in 15 years of angling I cannot recall ever seeing a trout open its mouth just before the food glided into it. Of course I know that trout must open their mouths to feed in the same way that I know they must rotate their pectoral fins in order to navigate. But I also appreciate the difference between knowing with my mind—perhaps with the aid of books—and knowing with my eyes. How much of a trout’s life is lived out of sight and, therefore, beyond knowing? 
I like Mill Creek for many reasons, one of which is that I can fish the whole day using dry flies ranging from ants to hoppers, regardless of whether a hatch is on or not. Right about now some readers are sitting up in their chairs, rubbing their chins, and furrowing their brows, if not in outright disbelief, then in the prelude to disbelief, which is doubt. Maybe these readers haven’t fished small streams. Small streams are small because they run through big land. Of course this is also true of rivers (the Colorado, for instance), but stream ecology differs significantly from river ecology. Mill Creek is enshrouded by vegetation, which often forms a canopy overhead and provides habitat for any number of terrestrials. But for those bugs that fall into the water below, the canopy also offers a death sentence.

Trout that live in these waters have therefore become generalists. Put simply, on a small stream, a multi-course dinner is pretty much always on the table throughout much of the year (In winter, Mill Creek flows in icy silence). In addition to the quantity of food, a trout’s feeding behavior is also affected by its orientation to the aquatic environment. It helps to imagine moving water as a conveyor belt that carries food. The extent to which the trout is compelled to take food items from the top of the belt is determined by availability, but it is also determined by the trout’s proximity to the food.

On a small stream like Mill Creek, which in most places isn’t very deep, a trout need only rise a couple of inches to reach the passing food item. But river trout typically shelter deep underwater, which means they must swim several feet to reach top water prey. Trout are curious animals, but if the goal is to conserve energy while maximizing caloric intake, river trout know to stay put unless the hatch is on.

Maximilian Werner lives in Salt Lake City. Look for new essays in “My Stories from Utah” regularly on this site.