Know Your Waters: Three Kinds of Rivers

When my son, Luke, played tight end for the University of North Dakota Fighting Hawks, he played football on two kinds of surfaces. All his home games took place on artificial turf in an indoor stadium. He even played on red turf at Eastern Washington University on a field dubbed “the Inferno.” But when he traveled to the University of Northern Colorado, the game took place on a natural grass field.

These two different kinds of surfaces — artificial turf and natural grass – required different kinds of cleats and different approaches.

This is true of the rivers you fly fish as well. While every place you fish is unique, you can group rivers into one of three kinds of rivers. The better you understand the characteristics of each type, the better you can make adjustments and set yourself up for success.

1. Freestone Rivers

Surface waters provide the main source of water for freestone rivers and streams.

This means rainfall and snow runoff.

Not surprisingly, then, freestone rivers rise and fall with the conditions. They can flood easily. When the spring temperatures warm and the snow melts, freestone rivers swell with water. This heavy water churns through the river or stream bed, displacing stones—hence the name “freestone.”

All this has a definite effect on fly fishing.

Of the three kinds of rivers, freestone streams may be the most volatile. Anglers must re-learn familiar stretches of river from year to year. A flood may scour out a larger undercut bank where large trout lie in wait for food. Alternatively, the same flood may deposit silt in a productive channel or run so that trout abandon it as a feeding lie.

Conditions can change rapidly, too.

I’ve had good fly fishing on Montana’s Yellowstone River one day, only to find it swollen the next day. In dry years, water levels drop, and water temperatures rise. This means staying off rivers when water temperatures creep into the high 60s. Fighting fish in such warm conditions endangers their lives.

One year, my podcast partner and I fished a creek that Dave and his brother had fished a couple years earlier with great success using hoppers. The stream is a smaller creek that flows into the Gallatin River. But the year Dave and I fished it, we could hardly find a run that was deep enough to fish. There was little snowfall the winter prior, and the creek was so low that the fish were bunched up in small pockets of water.

2. Spring Creeks

Since their main source of water is underground, spring creeks are more uniform in water level and temperature throughout the year. They typically flow through mineral-rich soil. This translates to significant aquatic plant growth which translates to an abundance of aquatic life (insects, scuds, crayfish, leeches, worms, etc.) which translates to a healthy fish population — both in terms of numbers and size.

The spring creeks I fish in the West and in the Midwest tend to have more silty areas than rocky areas. This makes for easier wading.

Spring creeks typically run crystal clear, so trout have the advantage.

When I used to fish Nelson’s Spring Creek south of Livingston, Montana, I found the trout to be more selective than spooky. These clear spring creeks have a few riffles, yet the runs tend to be gentle with slower current. Trout get a clear, long look at what you offer them. So fly size and tippet size matters.

In recent years, Dave, my podcast partner and I, have fished more spring creeks than freestones, given that we both now live in the Midwest. I’ve come to appreciate the more technical chops needed to catch fish in a spring creek.

3. Tailwaters

A tailwater is essentially the river or creek that flows out of a reservoir or lake created by a dam. These, these fisheries resemble spring creeks with their even flow. Because water is often released at the bottom of a dam where it is cooler and where the sediment is rich with nutrients, tailwaters can produce some large fish.

Tailwaters are often a bit off-color, so the fish tend to be less spooky.

I have been able to sneak up a lot closer to feeding fish in the Owyhee River in eastern Oregon — a fine tailwater full of brown trout—because it is slightly off color on most days. Like spring creeks, tailwaters resist the volatile swings that weather conditions create on freestone rivers. Conditions are more likely to change from of a discharge from a dam than from a snow runoff or a heavy rainfall.

So the next time you head to the river, identify its type. A little bit of understanding can go a long way towards success. All three kinds of rivers have their challenges, but all three are fun to fly fish.