Big Wood River Idaho
Copyright 2013 James Marsh
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Fly Fishing The Big Wood River In
The Big Wood River's name comes from the many
cottonwood trees that line the banks of the river. It is a
nice freestone stream that has a good population of
rainbow trout. The stream has several access point
most of which are off of Utah Highway #75 which
follows the river for most of its length. Fly fishing the
Big Wood River is convenient and easy to do, but the
catching isn't always so easy.

The river headwaters start near Galena Summit in the
Sawtooth Mountain Range. It flows between the
Pioneer Mountains and the Boulder Mountains and
Smoky Mountains before entering beautiful Sun
Valley. Its North Fork enters the main river about ten
miles north of Ketchum. Its East Fork, flowing from the
Pioneer Mountains, joins in on the flow below Ketchum
at Gimlet. From Sun Valley the river flows into Wood
River Valley and finally into Magic Reservoir.

Fly Fishing Big Wood River is affected by two things -
the snow pack and irrigation needs. Irrigation for
agricultural needs can drain the lower end of the
stream of much of its water affecting the water
temperatures and fishing. On wet years Where there
is lots of rain and a deep snow pack, fishing remains
good for the entire year. When there is a deep winter
snow pack, the runoff can last until near the end of

The rainbows and brown trout in the Big Wood River
have a lot of food to choose from and can be very
picky at times. There's lots of aquatic insects and
plenty of baitfish and sculpin. Mayflies, stoneflies and
caddisflies are plentiful. Matching the hatch or what is
about to hatch is often necessary if you expect much

The headwater sections of the river are quite different
than the larger section that flows through the valley.
Most of the upper part is fast, pocket water and on a
rather steep decline with the exception of some
meadow type areas with smooth flowing water. The
lower section is more of a classic run, riffle and pool

The Big Wood River is one of the easiest to fish
streams with plenty of wild trout in the state of Idaho. It
can be tricky at times, but paying attention to what is
the most plentiful and available food for the trout to
eat, and matching it with an imitation, will usually work
well. Add to that a little caution in staying hidden from
the trout and making good, upstream presentations,
and you will usually see consistent action from the
Type of Stream
Freestone Stream

Rainbow Trout
Brown Trout
Brook Trout

Central Idaho


Nearest Towns

General season Memorial Day
weekend to the end of November.
Some areas open year-round for
catch and release


Non-Resident License
State of Idaho

National Weather Service Link

Fly Fishing Gear and Trout Flies

Stream Flow Data:
USGS Real Time Data
Big Wood River Idaho
100% Satisfaction Guaranteed
Copyright 2016 James Marsh
Some areas are open year-round for
catch and release. You have to check
current regulations.
It is possible to fish the stream during the
winter but the fishing is usually tough.
Except for the runoff time, springtime is
great because of the hatches.
Fly Fishing Guide to the Big Wood
Most of the trout above Ketchum are
rainbows. There are some browns on the
lower end of the stream but they usually only
average around ten to twelve inches. The
river starts in the high mountains north of
Sun Valley and is a steeply declining stream
in most places above the North Fork
confluence.  It is fast moving pocket water
with smaller trout. Below the confluence it
begins to level out some and the flows
become more normal. The huge rocks
become few and far between and the
streambed is make up mostly of cobble and
smaller stones. The stream takes on a more
classic freestone appearance with long
pools, riffles and runs and of course, its
defining cottonwood trees along its banks.

The section of the river from the confluence
of the North Fork downstream for about
twenty-five miles to Bellevue is the most
popular area to fish. There is a diversion
dam below Bellevue that diverts the flow into
a channel so that it can be used for
agriculture irrigation. This diversion takes a
lot of the water during the hot summer and
creates some very low water conditions from
that point downstream to the reservoir. This
low water situation can make this section of
the stream unproductive at times.
Guide, continued:
Brown trout are more common in the
lower end of the river below Bellevue.
Above there, rainbows represent most of
the trout. There are only a few brown
trout in the middle and upper portions of
the river.

Theres also a tailwater section below
Magic Reservoir. Access to this water is
very limited. It is purely controlled by the
amount of water diverted for agriculture
irrigation. If the snow pack is good and
the rains come and provide what locals
call a wet year, fishing can be good below
the dam. During dry years it is hardly
worth fishing. This problem with the flows
keep the tailwater from being a prime

The freestone section of the Big Wood is
a very good trout stream with plenty of
hatches and plenty of trout. It has great
access. It is not large enough for drift
boats and most all of it can be waded with
ease. What more could anyone ask for.
Big Wood River Hatches and Trout
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 Wood 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.

Like many trout streams, the Big Wood
River has excellent hatches of Blue-winged
Olives that are about the most consistent
hatches that occur. They start in March and
last until mid June and then hatch again
during the fall months of September through
the first part of November.

The Green Drakes hatch starting around
the first of June and can last until mid July.
The smaller Western Green Drakes or
Flavs, start hatching about the first of July
and last until the middle of August. Another
consistent hatch is the Pale Morning Dun or
PMD hatch that starts occurring about the
middle of June. It can last through the
month of July.

Tricos begin hatching in the slow to
moderate sections of the Big Wood River in
mid August. They can last through
September. The Great Red Quills hatch
during the same time period or from mid
August through September. The little
Mahogany Duns start hatching the first of
September and can provide good fishing for
the entire month.

Stoneflies are an important part of the
trout's diet in the Big Wood River. Different
species of Golden stoneflies can hatch all
the way from May through October, peaking
at different times depending on the species.
Hatches, continued:
Yellow Sallies, or Little Yellow Stoneflies
hatch from about the middle of June,
through the middle of July.

Caddisflies are also very plentiful. The
Spotted Sedges are the most plentiful
species. They start hatching about the first
of June and last through the middle of
August. The next most abundant
caddisflies are the Green Sedges.  They
hatch from about the first of July until the
first of October. The larvae of these
caddisflies, or Green Rock Worms,
produce all season.

There are some Short-horned Sedges and
other species of caddisflies that hatch but
not in heavy concentrations.

Midges hatch throughout the year. Fish
can be taken year round on imitations of
their larvae, pupae and the adults but
most anglers use them during the cold
water times when few other insects are

Terrestrial insects such as grasshoppers,
ants and beetles become important about
the first of July. Imitations of them can be
effective through September.

The Big Wood River has plenty of sculpin,
minnows and baitfish. Streamer imitations
of work during the entire season,
especially when there is a little color to the
water. They also produce during low light

Perfect Flies have been used and tested
on this river on several occassions. They
not only are the most realistic trout flies
you can purchase, they are the most
effective at catching trout. We have
imitations of every type of trout food on
the Big Wood River. Please give them a
try if you haven't already done so.
After the runoff ends, anywhere from mid
to late June, the fishing is usually very
Fall may be the very best time for fly
fishing Big Wood River.
Big Wood River Idaho
Big Wood River Idaho
Thumbnail Images: Click to enlarge
Fishing Report Updated 10/13/16
(Bottom Of Page)
Big Wood River Fishing Report - 10/13/16
The stream levels are about normal for this time of the year. There are still some hatches
(mostly BWOs)
taking place and our customers are reporting some good catches.
Stream Conditions:

7 Day Weather Forecast:
There is a chance of snow everyday for the next week. Highs
will range from
29 to 45 degrees and lows from 26 to 35 degrees.

Recommended Trout Flies: We will update when the runoff ends
Rate: 202 cfs
Level: 1.43 ft
Afternoon Water Temperature: 51
Clarity: Clear
USGS Real-Time Stream Flow Data At Hailey ID
Brown and White Belly Sculpin Streamers, size 6
Midges: Blood (Red), sizes 20/22, larva, pupa and adults
Midges: Cream, size 20/22, larva, pupa and adults
Blue-winged Olives, size 18/16, nymphs, emergers, duns and spinners
Spotted Sedges, size 16/14, larva, pupa and adults
October Caddis, size 6, pupa and adults
Mahogany Duns, size 18, nymphs, emergers, duns and spinners
Japanse Beetles, 14/16
Carpenter Ants, 16/18
Sandwich Hoppers, Green, 8/10/12
Strategies, Techniques and Tips:
Brown Sculpin and White Belly Sculpin are great flies to use at this time of the year.
Midges are hatching - both cream and red, or blood midges.
Various species of Blue-winged Olive nymphs are plentiful and hatching, especially on
cloudy days.
Spotted sedges and green sedges, both caddisflies, are hatching.
Mahogany duns are hatching.
October Caddis are hatching.
Terrestrials, such as Japanese beetles, Carpenter ants, and grasshoppers are going to
become more and more important as the month goes by.
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.

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