Fly fishing Big Thompson River Colorado
Big Thompson River Colorado
Copyright 2014 James Marsh
Fly Fishing the Big Thompson River In
The Big Thompson River starts out as a very small
stream from many tiny tributaries near the Continental
Divide. The fishing starts near Moraine Park inside the
Rocky Mountain National Park where the stream splits
up into several channels. There is a public access
there. It is a willow lined small stream in an open
meadow with small brown, brook and cutthroat trout.

This section of the Big Thompson River is only free of
ice for about five months of the year. In the wide open
meadows, the stream has a large herd of elk. While
most trout in the Rocky Mountain Park are small, the
meadow section has some very nice size trout.

The headwaters of the Big Thompson River flows into
Lake Estes where additional water is added to its flow
from the opposite side of the Continental Divide via a
large pipe. The thirteen mile-long, 9-foot in diameter
tunnel brings water from Shadow Mountain Reservoir
on the Western Slope of the Rockies through the
Continental Divide and into the Big Thompson River.
Fly fishing the Big Thompson is a neat and usual fly
fishing experience, to say the least.

The section below the dam at lake Estes is probably
the most popular section. The section of the stream
flows through a canyon. There's a lot of public access
in this area including over forty public parking areas.
The fish average a better size there than they do
inside the Rocky Mountain National Park. There's a
ten mile-long "catch and release" section in this part of
the Big Thompson River which helps the fishery. The
lower section flows along highway #34 down to

Most of the Big Thompson River consist of pocket
water and riffles. Sylvan Dale Ranch has over two
miles of private water on the river. You can fish it but
you will have to pay. There are also several public
access areas along the river.

You won't hear much about fly fishing the Big
Thompson River until someone mention the great
flash flood that occurred there in 1976. Water came
roaring down the canyon and destroyed lot of property
and took more than one-hundred lives. That is
something that I'm sure isn't easy to forget.

Now-a-days, the Big Thompson River is as good of a
stream as there is in the front range. It also has a
variety of types of water and thanks to the tailwater,
can be fished more often than most other nearby
Colorado trout streams.

Seems the only ones well aware of the Big
Thompson's fly fishing opportunities are the locals and
they seem to want to keep that to themselves.
Type of Stream

Brown Trout
Brook Trout
Rainbow Trout
Cutthroat Trout

Medium, length 27 miles

North Central Colorado

Nearest Towns
Lake Estes


Fair to Good but tough in places

Non-Resident License
State of Colorado

National Weather Service Link

Hatch Chart
Perfect Fly Hatch Chart

Fly Fishing Gear and Trout Flies

Stream Flow Data:
Real Time USGS Data (Moraine
Real Time USGS Data (Andrews
Big Thompson
River Colorado
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The uppermost part of the stream stays iced
up for about half the year. The lower
tailwater section can be fished throughout
the year.
Spring is mostly midge and Blue-winged
Olive fishing but less tourists.  
Fly Fishing Guide to the Big
Thompson River
The spring runoff is from the end of May
through the month of June. It is just about
impossible to fish the river during this time.
The special regulation water between the
Estes Park and the Drake is what you would
call small stream pocket water. The fish are
mostly rainbow trout and brown trout that
probably average from ten to fourteen inches.
Most of them run around 12 inches. Most of
the trout are rainbows. The section below
Lake Estes at Estes Park is a tailwater. The
stream flows from the dam to Loveland. The
tailwater operates very stable for a dam
controlled lake. It can get some heavier
discharges during the late Spring and during
runoff (March - April) but for all practical
purpose, it is well controlled and the discharge
remain stable.

The trout in the Big Thompson regulated
areas are all wild trout. There has been no
stocking of trout by the state since 1994. The
trout are not pushovers that will take any dry
fly you present to them. You need to use light
leaders and tippets and make good
presentation with flies that imitate the insects
in the stream.
Guide, Continued:
As you will see in the Hatches and Flies
section, there are a surprisingly large
number of aquatic insects in the Big
Thompson. Most of the time, you will have
to pay attention to the insects that are
hatching or most available at the time.
Attractor flies work okay sometimes but
you are far better off using specific
imitations of the insects.

You need to keep in mind the tailwater
section flows along highway 34 which is a
very busy highway. During the tourist
season traffic headed to Rocky Mountain
National Park can be heavy and many of
the parking spots can be taken. If you
want to be alone or at least not crowded,
the best times to fish the river is early in
the season from March to April and then
again in September to October.
Big Thompson River Hatches and
Trout Flies:
Our information on aquatic insects is based
on our stream samples of larvae and
nymphs, not guess work. We base fly
suggestions on imitating the most plentiful
and most available insects and other foods
at the particular time you are fishing. Unlike
the generic fly shop trout flies, we have
specific imitations of all the insects in the Big
Thompson River and in all stages of life that
are applicable to fishing. If you want to
fish better, more realistic trout flies, have a
much higher degree of success, give us a
call.  We not only will help you with
selections, you will learn why, after trying
Perfect Flies, 92% of the thousands of our
customers will use nothing else.


Midges exist on the Big Thompson is huge
quantities and hatch throughout the year.
Imitations of their larvae, pupae and of the
adult work great and are very important
when nothing else is hatching.

The first mayfly hatches are the Blue-winged
Olives. They start hatching in April and
continue through the month of May. These
are bi-brooded insects that hatch again in
September and October.

Another important mayfly is the Green
Drake. These mayflies start hatching around
the first of July and last on as late as the end
of August. Red Quills also hatch during the
same time period. They can be just as
important as the Green Drakes.

Golden Stoneflies hatch starting about the
middle of June and last through August,
depending on the area of the river you are
fishing. Yellow Sallies, or Little Yellow
Stonefies, start hatching in late May and can
last well into August.

There are several species of caddisflies.
The first important ones to hatch are the
Little Black Caddis from the
Hatches, continued:
These Grannom caddisflies start hatching
about the first of May. It usually last about
a month. This hatch starts in the lower
elevations and works upstream.

During June, July, August and September,
you will find different species of Spotted
Sedges, or net spinning caddisflies. There
are also a few of their Little Sister Caddis.
The Little Sisters hatch during the month
of July. Little Short-horned Sedges hatch
in late May and  early June. They are the
little caddisflies that crawl up your waders.
Theres also species of Green Caddisflies,
or Green Sedges, as they are often
called. The larvae of these caddisflies are
called Green Rock Worms. Imitations of
them are very effective from about June
through August. There are few other
species of caddisflies present in the river,
but none of them hatch in large quantities.

Terrestrial insects become important
during the months of June, July, August
and September. Imitations of grasshopper,
ants and beetles are all effective during
these months during this time.

Theres a lots of Sculpin in the river and a
few different species of minnows and
baitfish. The streamers are very effective
when the brown trout start to spawn in the
fall. They also work anytime the river is a
little off color from rain as well as early in
the morning and late in the afternoons.

If you haven't tried our "Perfect Fly" trout
flies, we suggest you do. We have specific
imitations of everything that hatches on
the Big Thompson River. Please check
them out. We are confident that you won't
be disappointed.
Summer is the best time to fish the river but
it can be crowded.
Early fall is great fishing and less tourists.
Fly fishing Big Thompson River Colorado
Fly fishing Big Thompson River Colorado
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(Bottom Of Page)
Fishing Report Updated 06/13/14
Big Thompson River Fishing Report - 06/13/14
The Big Thompson is in much better shape.

Stream Conditions at 06/13/14:

7 Day Weather Forecast:
There is a slight chance of rain Saturday, otherwise clear. Highs
will range from
66 to 72 degrees and lows from 35 to 42 degrees.

Recommended Trout Flies:
Rate: 2650 cfs
Level: 5.24 ft
Afternoon Water Temperature: 51
Clarity: Clear
Stream Flow Data Below Moraine Park near Estes Park CO
Blue-winged Olives, size 16/20, nymphs, emergers, duns and spinners
White Belly and Brown Sculpin streamers, size 6
March Browns, size 14, nymph, emergers, duns and spinners
Golden Stoneflies, size 10/12, nymphs and adults
Spotted Sedges, size 14/16, larva, pupa and adults
Western Green Drakes, size 10/12, nymphs, emegers, duns and spinners
Dark Red Quills, size 14, nymph, emergers, duns and spinners
Green Sedges, size 14/16, larva, pupa and adults
Little Yellow Stoneflies, size 14/16, nymphs and adults
Strategies, Techniques and Tips:
Blue-winged Olives nymphs are plentiful and a fly we recommend at this time. The Black
Matuka Sculpin and Olive Matuka Sculpin streamers are good flies to use for the larger
trout. Crawl them on the bottom of the deepest water. March Browns are still hatching in
some areas. Golden stoneflies could begin to hatch anytime now. Western Green
Drakes and Dark Red Quills will start to hatch when the water temperature reaches
about 55. Green Sedges and Spotted Sedges (caddisflies) usually start hatching about
his time. Little Yellow Stoneflies will also begin to hatch when the water is about 55
Options For Selecting Flies:
1. Email us (
with the dates you will be fishing this
stream and we will send you a list of our
fly suggestions. Please allow up to 24
hours for a response.

2. Call us 800-594-4726 and we will help
you decide which flies you need.

3. Email us (
with a budget for flies and we will select
them to match the budget and get them to
you in time for your fly fishing trip.

All orders are shipped free in the
U. S. Orders over $50 are shipped via
Priority Mail.  
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