Straight Fork Journal:

Stream Water Temperatures (8/14/07):
Angie and I just returned from Wisconsin where we had been fishing the lovely
small spring creeks to find several emails from this website as well as our
Yellowstone website ( regarding
water temperatures in both parks. In general, they were concerned about the
very high temperatures and low water conditions in both locations.
Normally this time of year we fish early in the mornings in the park. I say normally
and that is really not the case because normally we are in the Yellowstone area.
Last year we spent most of August and September fishing inside the Yellowstone
Park working on a video we will have available this fall. We stopped early this
year and returned home and will return there in mid September through October.
When I say we fish early I mean from not long after sunrise to about 9:00 AM.
The low water temperatures and low light conditions are usually favorable. Due
to the emails and situation in the park, yesterday, we left early and first stopped
at the lower end of the West Fork of the Pigeon River near Gatlinburg.  The
water temperature was sixty-eight degrees.
Now there is absolutely nothing wrong with fishing under those conditions but we
choose to move on because of the fact that when water reaches the high sixties
it becomes much more difficult to catch trout. This is especially true with the
added difficulty of low water conditions.
The low water conditions are also responsible for the water temperatures
changing very fast. It takes less time for the water to adjust towards the air
temperatures when there is less water.
Stopping again at the Chimney area, we found the water temperature to be
sixty-six degrees. In a few short minutes we were able to catch a couple of
rainbows but we choose to move on.
Our next stop was at the Straight Fork not far inside the park. It took a lot of our
early morning time just to get there but it was worth it. The water temperature
was sixty-four degrees. By the way, we have both an analog and a digital
themometer that we double check with each other to make sure we are getting it
right. Also, just in case you are not familiar with the stream, the elevation we
fished was 2850, which is not far inside the park.
We always have a handheld GPS handy. By the way, the particular one we used
has highly detailed maps of the park as well as satellite imagery. I mention the
elevation because that is higher than most of the streams that exit the park and
is of course a factor in the lower water temperatures.
The next hour produced eight fish -  one brown and the others rainbows.
Only one of us fishes at a time. All of them took a size 20 blue-winged olive
spinner. Although we were not certain, we figured if any thing was hatching, it
would be the Little Blue-winged olives. These are not the large Eastern
blue-winged olives or Drunella species and they are not Baetis species. They
could be one of several other genera of the Baetidae family. The spinners fall
late in the day and sometimes early in the mornings. We have no way of knowing
if the fly was a factor or not, we simply used something we figured the trout were
used to seeing and it worked fine. We probably missed more fish that we caught
because you cannot see the small, spent wing fly in the low light conditions at all.
On the way back home we stopped at about 10:30 AM and checked the
Oconaluftee River water temperature at the point the stream leaves the road. It
was sixty-eight degrees.
One email asked "at what water temperature they should stop fishing".
Provided reasonable care is taken, there is nothing wrong with catching trout on
the fly with water temperatures up to the low seventies if you care to try. The
problem is, it will not be easy. When temperatures reach the low seventies, the
fish almost cease feeding. The problem is not the water temperature as such, it
is the low oxygen levels associated with the warm water. The temperature of the
water and the oxygen content are inversely proportional. It doesn't change on a
straight line. It changes on a sharp curve. The higher the water temperature the
lower the oxygen level.
Studies done on the Firehole River in Yellowstone National Park have shown
that when the water is in the low seventies, the trout will actually lose weight.
They simply do not feed as much.
The solution is to find cooler water but if you insist fishing in water in the high
sixties or low seventies (which we do not recommend because of the increased
difficulty), find the highly oxygenated areas of the water - water falls, plunges,
Regarding the question of whether or not it hurts the fish to catch them in water
as high as lets say seventy degrees, the answer is no - not if reasonable care is
taken. By that we mean if the fish is released quickly after being caught, they
should be fine. When water temperatures is in the low seventies, it is best to
leave the fish alone. The point at which high temperatures can hurt the fish
varies from species to species, area to area and exactly how much stress is put
on the fish during the catch and release. As a general rule, we would say that
when the water is close to seventy degrees, it is best to stop fishing.  
Some believe that they swim off and then die. That is possible of course, but not
probable. When a fish that is overextended, so to speak, revives and swims off,
it is usually fine. Don' try to revive them. Just release them quickly.
What does hurt the fish, especially at high water temperatures (and air
temperatures after being caught) is keeping them out of the water a long time.  
Far worse is mistreating them. I see photos all the time where people have laid
trout on the ground (usually by their rod) and photographed them. That is not
All fish have a slimy coating on them that helps protect them. It helps prevent
fungus for one thing. It is easily removed from their outer body. Handling them
with dry hands and/or a dry landing net can do it. Always wet your hands and net
before landing fish. Laying them on the ground or any dry object can remove
portions of it.
We should also mention that you should not fight a fish a long time on ultra light
tippets under warm water conditions as this adds to the stress. This is usually
not a problem in the Smokies because the fish are usually small and can be
caught quickly. If a large brown is caught and fought for a long time, it can be
over stressed. So it is possible to do that.
If you go early, check the water temperature, fish at higher elevations you
should do well in the park. Just use common sense and take care of the fish.

Copyright 2007 James Marsh