There are different types of trout streams that fly fisherman wade and float in pursuit of trout from freestone rivers like our Eagle to dam controlled tailwater rivers like the Frying Pan. Freestone rivers have a certain kind of magic for anglers since they’re flows are uncontrolled, they support diverse insect life and often they flow through beautiful country.
What is a Freestone River
In the Colorado high country our most common water source is snowmelt while other mountainous areas of the country may have spring fed freestone streams, our freestone rivers are primarily caused by melting snow. When rainwater and snow melt gravity forces these droplets to seep through the crevices of rocks, soil and organic matter, they combine into small trickles of water. Eventually thousands of water trickles add up to a small creek which combines with other creeks to form small streams which combine with other streams to form small rivers and eventually dump into a large rivers.
Water flows increase drastically in the spring time and high flows matched with steep gradients send rocks tumbling on other rocks down river. These rocks also do a great job at disintegrating all the fallen trees and their leaves into micro nutrients the bugs require. The rock themselves add valuable minerals to the waterway when they are pulverized during their decent downstream.
The benthic zone or the river bottom is characterized in a freestone river by the smooth rocks, large boulders, gravel and sand. The fast moving water inhibits the growth of weeds and other rooted vegetation resulting in a “free stone” river bottom. It is also important to note that freestone rivers are not controlled by dams and do not flow out of man made reservoirs. Streams such as these are “tailwaters” and have been discussed in an earlier blog.
Anatomy of a Freestone River
Not many species of macro invertebrates (trout food) can live in the upper headwaters of these freestone waterways because of the steep gradients and ultra-fast currents. Hence we see many smallish trout in the headwaters of a freestone river.The headwaters are categorized by extremely fast currents and many drop pools, fish can be found where they can be safe and eat. Usually fish are located in the deepest sections of the creek but can be found anywhere you might look for an opportunistic trout like an undercut bank, large boulder or overhanging bush.Typically midge larva, web building caddis and a few smaller golden stonefly species are found in the upper reaches of a freestone stream.
Still descending down, freestone rivers tend to get larger and larger as more tributaries enter the main flow. Less and less large boulders cover the river bottom and more small rocks, sand, gravel and silty bottoms begin to appear. Often there is a riffle, run, pool construction to the river here and typically these areas are the most productive reaches with high trout populations and larger fish due steady hatches, good habitat and cover, deep wintering holes and good spawning gravel. Fly fishing tactics vary here with hatches and the seasons.
The slower currents finally reaching a point where the slow water tends begin winding in large S turns sometimes even creating oxbow lakes. The bottom tends to consist of sand, gravel and mud as currents slow. Trout numbers tend to drop off in these sections but usually there are some very large predatory trout in these marginal areas. Streamers are a good bet here. Sometimes in the lowest reaches of freestone river, water temperatures may sometimes warm to a deadly level during late summer, where it will not hold enough dissolved oxygen for trout to survive.
This is exactly how our own Eagle River changes over the course of it fifty mile jaunt through Vail Valley and the Rocky Mountains. Freestoners are productive but can be challenging because conditions change rapidly, sometimes on a daily basis. Temperature swings, seasonal shifts, overlapping hatches are all common occurrences. Additionally, flows range widely throughout the year with the lowest flows during the coldest part of winter gradually rising through spring, peaking in late spring and slowly dropping through summer and fall. Large rainstorms can also bump up flows for short periods. Getting to really know a freestone river and its habits can take time. Hiring a guide can be a great idea.
With a short seasonal feeding window and limited amount of bug life the trout will rise eagerly to attractor dry flies. Some of my favorite headwater terrestrial bugs to imitate are ants, beetles and smallish grasshoppers. Best to use hook sizes in the 10, 12 and 14 range so you can see the artificial while floating in a small creek and the naturals run about those sizes. Most of the upper headwater creeks in Central Colorado are teaming with small native cutthroat trout, brown trout, rainbow trout and brook trout ready to reward the avid hiker with plenty of dry fly opportunities.
Anglers need to change their methods of fishing as drastically as the stream changes in size when they head down stream to bigger water. A larger wider variety of aquatic life including a range of insects and small fish exists in the stream here providing more opportunity for the trout to grow faster. As the streambed widens the fish have more to eat and have to expend less energy to survive. Boulder strewn pocket water is the norm in these sections of river, as deeper pools allow fish more protection. Nymphing, streamers and dry flies will all attract fish in this type of water.
Other fantastic freestone fisheries that Vail Valley Anglers fish and guide on include the Gold Medal Roaring Fork River and Gore Creek. Stop by the fly shop in Edwards for river maps and advice on where and how to catch trout.