High Water occurs after heavy
rains and/or when the rainfall
amounts are above average.
To much water can also be
bad for Yellowstone in all
respects, including the trout.
Floods destroy the aquatic
insects, redds, and other
things trout rely on.  
Freestone Streams
...........................             .Fly Fishing  Yellowstone National Park
A freestone stream is born at the top of mountains as drops of rainwater and
melting snowflakes. As gravity forces these droplets to seep through the crevices of
rocks, soil and organic matter, they combine into small trickles of water. Some of
this water stays on the surface and some sinks into the ground to later emerge as a
tiny spring. These trickles eventually collide and become larger and larger. They
form tiny streams that you can step across. The tiny streams eventually join other
tiny steams to form larger ones. These tiny streams are made larger along the way
by many other trickles of water and eventually become streams that are large
enough to be named and shown on maps. These streams are usually the
headwaters of what will become a large freestone stream or river. The
PH of the
water is usually low.
Generally, water in the headwater streams is fast moving pocket water. Most
headwaters fall through steep gradients and rapidly flow downhill. As the stream
reaches the lower elevations of the foothills the gradients become less and less
and the flow of the water decreases accordingly. As more and more water collects
the streams become wider. The water in the larger streams slows as it moves
through the valley.
As the stream reaches the lower elevations of the valley and the flows decrease, the
temperature increases. Eventually the water will become too warm to support trout
and other warm water species of fish such as smallmouth bass will become more
prevalent. The slower moving water will not hold as much dissolved oxygen as the
faster moving headwaters. This also becomes an important factor in the stream’s
ability to support trout.
Copyright 2007 James Marsh
The water level in this
stream is about normal. In
order to fish freestone
streams successfully, you
have got to be flexible. In
other words, you need to be
able to go with the flow.
It is difficult to conceive this
size stream starting out as  
tiny springs near the top of
the high mountains in the
park but it did. Anglers need
to change their methods of
fishing as drastically as the
stream changes in size.
have large pools like this one.
And this large pool