Elizabeth
Materna
To:
Allen.
Adrianne@
epamail.
epa.
gov,
cohon.
keith@
epamail.
epa.
gov,

siciliano.
carolann@
epamail.
epa.
gov,
Keenan.
Dru@
epamail.
epa.
gov,

09/
24/
2003
03:
23
Palmer.
John@
epamail.
epa.
gov,
lalley.
cara@
epamail.
epa.
gov,
Kay
Dawn
Mar/
NIFC/
BLM/
DOI@
BLM
PM
cc:

Subject:
bull
trout
spawning
criteria
Here
is
a
description
of
the
bull
trout
spawning
criteria
issue
and
some
related
information
from
our
Bull
Trout
Recovery
Plan,
October
2002.
Issue
For
most
areas
of
bull
trout
spawning
and
rearing
where
numeric
criteria
of
12C
as
the
7DADM
apply,
we
are
assuming
that
the
appropriate
spawning
temperature
will
be
reached
as
the
fall
season
progresses.
Bull
trout
spawning
typically
occurs
from
August
to
November
during
periods
of
decreasing
water
temperatures.
However,
reservoirs
can
interrupt
the
natural
cooling
pattern/
process
that
the
assumption
is
based
upon
and
thus,
we
need
to
be
able
to
ensure
that
water
temperatures
for
BT
spawning
areas
below
reservoirs
are
at
the
appropriate
temperatures
(
9C)
during
spawning
times.

During
the
EPA
Region
10
Temperature
Criteria
Guidance
Project,
a
panel
of
experts
investigating
different
aspects
of
bull
trout
temperature
requirements
was
assembled
to
review
information
related
to
the
range
of
optimal
temperatures
for
bull
trout
and
risks
associated
within
and
beyond
the
range.
The
Bull
Trout
Temperature
Criteria
Peer
Review
Panel
was
specifically
asked
if
establishing
a
separate
spawning
season
criteria
was
warranted.
The
panel
did
not
feel
it
would
be
appropariate
to
establish
a
separate
spawning
criteria
with
the
possible
exception
of
regulated
rivers
(
i.
e.
those
with
dams).
US
Fish
and
Wildlife
Service
(
FWS)
Bull
Trout
Recovery
Unit
Team
lead
biologists
for
Oregon
were
separately
surveyed
about
this
issue
and
they
also
felt
that
a
separate
spawning
criteria
was
not
necessary
except
where
spawning
areas
occur
below
dams.

FWS
Bull
Trout
Recovery
Unit
Team
lead
biologists
were
asked
to
identify
dams
or
reservoirs
above
spawning
areas.
They
identified
the
following
four
dams:
Clear
Creek
Reservoir
and
Mehlhorn
Reservoir
on
upper
Clear
Creek
in
the
Pine
Subbasin
(
Powder
Basin);
Laurance
Lake
(
Clear
Branch
Dam)
on
the
Middle
Fork
Hood
River
(
Hood
Basin);
and
Carmen
Reservoir
on
the
upper
McKenzie
in
the
Willamette
Basin.
The
corresponding
spawning
times
from
ODFW
timing
information
is
as
follows:
Hood
Basin
(
Middle
Fork
Hood
River)
peak
use
Sept.
15­
Oct.
30
and
lesser
use
Aug.
15
to
Nov.
30;
and
McKenzie
(
above
Blue
River)
peak
use
Sept.
1­
30
and
lesser
use
Aug.
15­
Oct.
30.
There
are
no
timing
tables
for
the
Powder
Basin
(
Pine
Creek)
but
Paul
Bridges
of
our
office
(
Recovery
Unit
Team
lead
biologist
for
the
John
Day
Basin
with
much
on­
the­
ground
experience)
said
Sept.
1
would
be
an
appropriate
start
date
and
Oct.
31
an
adequate
end
date.

General
Background
Dams
affect
bull
trout
by
altering
temperature
regimes.
Manipulated
flow
releases
from
storage
projects
alter
the
natural
flow
regime
and
affect
water
temperature.
The
effects
of
the
myriad
of
small
irrigation
diversion
and
hydropower
projects
throughout
the
range
of
bull
trout
are
likely
of
even
greater
significance
than
the
large
hydropower
and
flood
control
projects.
Many
of
these
are
located
further
up
in
the
watersheds
and
can
periodically
dewater
a
downstream
reach.
Even
if
diversions
are
not
so
severe
as
to
dewater
downstream
reaches,
reduced
flows
can
result
in
thermal
passage
barriers.
The
prevalence
of
these
structures
throughout
the
range
of
bull
trout
has
contributed
to
isolation
of
bull
trout
populations
to
the
upper
watersheds
in
many
areas.

Although
bull
trout
are
widely
distrubuted
over
a
large
geographic
area,
increased
habitat
fragmentation
reduces
the
amount
of
available
habitat
and
increases
isolation
from
other
populations.
When
species
are
isolated
by
fragmentation,
low
rates
of
population
growth
are
typical
in
local
populations
and
their
probability
of
exinction
is
directly
related
to
the
degree
of
isolation
and
fragmentation.
Without
sufficent
immigration,
growth
for
local
populations
may
be
low
and
probablility
of
extinction
high.
There
is
more
genetic
divergence
among
bull
trout
than
among
salmon,
indicating
less
genetic
exchange
among
bull
trout
populations.
Bull
trout
are
isolated
in
the
headwaters
of
tributaries
and
where
migratory
bull
trout
are
not
present,
these
isolated
populations
cannot
be
replenished
when
a
disturbance
makes
local
habitats
unsuitable.

Basin
Specific
Information
Pine
Creek
subbasin
has
depressed
resident
populations
of
bull
trout.
Maximum
estimated
abundance
for
bull
trout
was
less
than
400
individuals
for
each
stream.
Numerous
water
diversions,
ditches,
and
reservoirs
have
been
constructed
to
supply
water
for
the
irrigated
agriculture
and
ranching
activities
that
occur
here.
Many
of
these
structures
have
created
unsuitable
habitat
conditions
including
elevated
water
temperatures.
In
the
Pine
Creek
subbasin
there
are
12
reservoirs
which
may
be
sufficiently
raising
water
temperatures
downstream
so
that
bull
trout
distribution
is
affected.
Habitat
fragmentation
has
resulted
in
isolated
groups
of
bull
trout
in
this
recovery
unit.

Bull
trout
populations
in
the
Willamette
Recovery
Unit
are
exposed
to
greater
risk
of
extinction
because
of
their
small
population
size
and
physical
isolation
and
they
are
below
the
numbers
that,
in
current
population
theory,
are
thought
to
represent
a
viable
population
(
minimum
of
1,000
adult
spawning
individuals)
to
minimize
inbreeding
effects
and
maintain
an
ability
to
adapt
to
changing
evnironmental
conditions.
Spawning
and
rearing
habitat
is
in
the
mainstem
McKenize
River
above
the
Trail
Bridge
pool.

Clear
Branch
Dam
(
Laurance
Lake)
in
the
Middle
Fork
Hood
River
has
isolated
bull
trout
above
and
below
the
dam.
The
relatively
warm
impounded
waters
increase
stream
temperatures
below
the
dam
beyond
those
suitable
for
bull
trout
at
certain
times
of
the
year.
The
draft
recovery
plan
states
that
Bull
trout
in
the
Clear
Branch
of
Hood
River
occur
primarily
above
the
Clear
Branch
Dam,
however
comments
collected
during
the
public
comment
period
indicate
that
it
provides
spawning
and
rearing
habitat
below
the
dam
as
well.
Migratory
life
forms
persist
in
at
least
some
local
populations
with
partial
ability
to
connect
with
other
local
populations
resulting
in
this
area
categorized
as
at
an
intermediate
threat
level.
