Tailwater vs. Freestone Rivers: How do they differ?

In the fly fishing world, typically we classify fish holding rivers/streams in three different categories, tailwaters, freestones, and spring creeks. So how do they differ and why should we care? Well, in fact, each classification is very different and typically supports different biology based on the amount of oxygen, vegetation, entomology and a lot of scientific facts that is beyond my understanding. But, as anglers, it is important to understand the basics of the differences between these classifications as our tactics typically will be different. Some proper preparation will lead to a more successful day on the water.

Tailwater Fisheries

Flaming Gorge Dam
The Flaming Gorge Dam on the Green River

A tailwater is classified as a dam controlled piece of water. The dam controls the flows and thus the temperatures. Man and computers typically regulate the flows and discharges from the dam. There are many famous tailwater trout streams throughout the states. To name a few, the Green River, Missouri River, Frying Pan River, Blue River, South Platte, North Platte, Madison River, San Juan River, Bighorn River, Yellowstone River, and even the Colorado River. They are famous for the quality trout fishing with large populations of trout and bigger on average fish. On the Green River, there are 22,000 trout per mile in each of the first 6 miles of the river below the Flaming Gorge Dam. That is a lot of trout!

So why are there typically more fish and larger ones in tailwater systems?

Well since the flows are regulated, the temperatures do not fluctuate as much. Thus, there is more bio-productivity meaning larger concentrations of bugs, plants, and just biomass. With all of this biomass large populations of trout are able to thrive and the trout have enough food to eat a lot and grow larger.

Here are a few pointers I like to keep in mind when fishing tailwaters:

  • Tailwaters typically receive more angling pressure from other rivers. Be ready for crowds.
    • Get to your desired fishing area early
    • Be courteous and kind with other anglers
  • Know the bug life! Do your research before traveling to a specific tailwater. A lot of times there can be a variety of different bug life that is not present on freestone rivers like Mysis Shrimp, Scuds/Sow Bugs, and Aquatic Worms.
  • Typically since the water temps are more stable it is easier to predict the hatches. So like above do some research.
  • Get technical with it. Since these systems typically receive more angling pressure than others the fish can be harder to fool. Fluorocarbon can lead to more success, using fluorocarbon tippet and even a fluoro leader can lead to more success when nymphing. Fly selection can be more important, getting to that right size bug can make or break the day.
  • Winter is go time! Since the flow is regulated, the river never ices over. My favorite time to visit a tailwater is in the colder months as the crowds are usually not bad and the fish are still very active. Check out these blogs on these different tailwater fisheries right here in our backyard.
  • Tailwaters typically aren’t impacted by runoff as much as freestone systems. While the flows typically do rise on tailwaters during runoff they usually are more friendly than the freestone rivers.

While many tailwaters across the West typically mean productive trout fishing, this is due to the proper management of the river flows. Fortunately, many of the dams have regulations and standards in place that help sustain a healthy fishery. If flows in the summer aren’t high enough this can result in rising temps and fish kills as well as if too much water is released it can result in thermal shock to the fish. But, if managed properly they can provide anglers with some phenomenal trout fishing.

Freestone Fisheries

Eagle River
The Eagle River here in our backyard

The wild freestone fisheries are systems that are fed by rainfall and snowmelt and entirely dependant on the natural water supply. The flows of a freestone river fluctuate constantly and are entirely at mercy of mother nature. The Eagle River and Gore Creek are prime examples of freestone rivers as they are completely dependant on the natural water supply. If we have a bad snowfall year in the area, we should expect lower flows and warmer water. If there are periods of not a lot of rainfall in the summer the Eagle River’s flows will drop and the temperatures will warm. This happened this past summer and fishing conditions were challenging due to the high water temps.

So how does fishing a freestone differ than a tailwater?

Since the flows and water temps are constantly changing, tactics for fly fishing can change with a flick of a switch. The bug life and hatches are all dependant on water temps. When the water hits that certain mark, a certain species of insects will begin hatching. Typically on a year to year basis you can expect similar hatches but you can never be never certain.

What are some tactics to keep in mind when fishing freestones?

  • Watch the weather. Be sure to be watching the weather closely when planning your freestone fishing trip.
    • A night full of heavy rain in the summer can fluctuate the flows and “blow out” the river causing off color water.
    • A couple days of warmer temps in the winter is game on for fishing conditions.
  • The trout are opportunistic. The fish in these systems have to work hard for their food. Get that fly in front of them. Typically trout are less picky in freestone systems.
  • Since they are natural systems, sticking with more natural tactics like big bushy dry flies drifting through fast water can get the job done. No need to get too technical.

Why many anglers prefer freestones?

  • These fish work there butt’s off to stay alive, through the muddy stream blowouts, to the below freezing temps. The fish in these systems are true warriors.
  • They are at the mercy of mother nature. Which can mean every year is different and sometimes you don’t know what to expect. Embrace every new challenge.
  • They are natural untouched systems.

Pro Guide Tip:

A thermometer is a freestone angler’s best friend. Checking the temp throughout the day can give you an idea of the bug hatches and what to expect. It can also be a great tool to know when to stop fishing due to warm temperatures.

Spring Creeks:

Spring Creek

Spring creeks are probably the most irrelevant in the Vail fishing region as spring creeks are solely fed by groundwater seepage of natural and nutrient rich spring water. While there are a variety of different groundwater fed streams in the Rockies most of them are also fed by snowmelt. Thus, making them not your classic “Spring Creek.” While you will find some especially on private property in the high country. If you do find yourself fly fishing a spring creek here are some points to keep in mind.

  • The fish are typically very spooky as the water is gin clear and a low flow. So longer leaders, lighter tippet, and delicate presentation is key.
  • Start small, typically the insects on spring creeks are smaller than other river systems. So smaller sized flies can be the ticket. At times these fish can be very selective as they are in tune with the exact bug life that is occurring. So be sure to study your surroundings.

Eagle River Shot

While many of these different river systems can be a mix of all three different systems (Like the Colorado River). From spring creeks to some sort of regulated flow/dam to a snowmelt tributary it is important to identify what type of fishery you will be fishing in order to better prepare for your trip. Each system can provide unique challenges for every angler, as fly fishers, I guess that is part of the fun.

For up to date conditions on the local rivers be sure to check out our fishing report. Feel free to call the shop for river conditions and reports on the local tailwaters like the Frying Pan River, Yampa River, and Blue River.

Patrick Perry Former Guide and Content Contributor @patperry