Factors
for
Decline
A
Supplement
to
the
Notice
of
Determination
for
West
Coast
Steelhead
Under
the
Endangered
Species
Act
National
Marine
Fisheries
Service
Protected
Species
Branch
525
NE
Oregon
Street
­
Suite
500
Portland,
Oregon
97232
and
National
Marine
Fisheries
Service
Protected
Species
Management
Division
501
West
Ocean
Blvd.,
Suite
4200
Long
Beach,
California
90802
August,
1996
TABLE
OF
CONTENTS
Introduction
to
the
Endangered
Species
Act
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1
Summary
of
Events
Leading
to
the
Steelhead
Status
Review
.
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2
Factors
Contributing
to
the
Decline
of
Steelhead
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6
I.
The
Present
or
Threatened
Destruction,
Modification,
or
Curtailment
of
Steelhead
Habitat
or
Range.
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6
A.
Hydropower
Development
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6
1.
Juvenile
Steelhead
Passage
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7
2.
Adult
Steelhead
Passage.
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8
B.
Water
Withdrawal,
Conveyance,
Storage,
and
Flood
Control
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9
C.
Land
use
activities
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13
1.
Logging
and
Agricultural
Activities
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14
a.
Loss
of
Large
Woody
Debris
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15
b.
Sedimentation
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17
c.
Loss
of
Riparian
Vegetation
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21
d.
Loss
of
Habitat
Complexity
and
Connectivity
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24
2.
Mining
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25
3.
Urbanization
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27
II.
Over­
utilization.
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28
A.
Commercial,
Recreational,
and
Tribal
Harvest.
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28
B.
Scientific
Utilization.
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31
C.
Ocean
Harvest
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32
III.
Disease
or
Predation.
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33
A.
Disease.
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33
B.
Freshwater
Predation.
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36
C.
Marine
Predation.
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38
IV.
Inadequacy
of
Existing
Regulatory
Mechanisms.
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40
V.
Other
Natural
and
Manmade
Factors.
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40
A.
Natural
Factors
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40
1.
Drought
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40
2.
Floods
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42
3.
Ocean
Conditions
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43
a.
El
Niño
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46
4.
Other
Natural
Occurrences
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47
B.
Manmade
Factors
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48
1.
Artificial
Propagation
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48
Summary
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51
Literature
Cited
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57
Appendix
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80
Acknowledgements
The
authors
would
like
to
thank
the
numerous
reviewers
of
this
document
for
their
useful
comments
and
insights.
In
particular,
special
thanks
goes
to
the
states
of
California,
Idaho,

Oregon,
and
Washington,
the
U.
S.
Fish
and
Wildlife
Service,
and
the
Northwest
Indian
Fisheries
Commission
for
their
critical
review
of
this
document.
The
authors
would
like
to
thank
internal
NMFS
reviewers,
including
the
Coastal
Zone
and
Estuarine
Science
Division,
located
in
Seattle,

Washington,
and
the
Habitat
Branch
of
the
Environmental
and
Technical
Services
Division,

located
in
Portland,
Oregon.
The
authors
would
also
like
to
thank
Dan
Logan
and
Katie
Busse,

interns,
for
their
editorial
review
of
this
document.
1
16
U.
S.
C.
§
§
1531­
1544
(
1994).

2
"
Take"
is
defined
under
the
ESA
as
"
to
harass,
harm,
pursue,
hunt,
shoot,
wound,
kill,
trap,
capture
or
collect,
or
attempt
to
engage
in
any
such
conduct."
16
U.
S.
C.
§
1532
(
19)
(
1994).

3
16
U.
S.
C.
§
1532
(
15)
(
1994).

4
50
CFR
§
424.02
(
k)
1995.

5
50
CFR
§
424.02
(
m)
1995.

6
50
CFR
§
424.02
(
e)
1995.

1
Introduction
to
the
Endangered
Species
Act
The
Endangered
Species
Act
of
1973
(
ESA)
1
provides
a
framework
for
identifying
species
that
are
in
danger
of
(
or
threatened
with)
extinction.
The
ESA
imposes
obligations
on
Federal
agencies
to
prohibit
actions
that
might
jeopardize
a
listed
species
and
directs
agencies
to
use
their
authorities
to
promote
the
conservation
of
listed
species.
Further,
the
ESA
imposes
restrictions
on
the
activities
of
all
persons
that
might
result
in
the
taking,
2
either
directly
or
indirectly,
of
listed
species.

The
ESA3
divides
responsibility
for
listing
species
between
the
Secretary
of
the
Interior
and
the
Secretary
of
Commerce.
Essentially,
the
Secretary
of
the
Interior
is
responsible
for
all
terrestrial
and
freshwater
species
while
the
Secretary
of
Commerce
is
responsible
for
all
marine
species.
In
some
cases,
such
as
for
sea
turtles,
the
two
departments
share
jurisdiction.
The
Secretary
of
the
Interior
has
delegated
his
authority
under
the
ESA
to
the
United
States
Fish
and
Wildlife
Service
(
FWS).
The
Secretary
of
Commerce
has
delegated
his
authority
to
the
National
Marine
Fisheries
Service
(
NMFS).

The
NMFS'
ESA
implementing
regulations
define
a
"
species"
to
include
any
species
or
subspecies
of
fish,
wildlife,
or
plant,
and
any
distinct
population
segment
of
any
vertebrate
species
that
interbreeds
when
mature.
4
A
"
threatened"
species
is
defined
as
any
species
in
danger
of
becoming
endangered
in
the
foreseeable
future;
5
an
"
endangered"
species
is
defined
as
a
species
in
danger
of
extinction
throughout
all
or
a
significant
portion
of
its
range.
6
2
The
ESA
allows
listing
of
"
distinct
population
segments"
of
named
species.
According
to
NMFS
policy,
a
salmon
population
or
group
of
populations
is
considered
"
distinct"
and
hence
a
"
species"
under
the
ESA
if
it
represents
an
ESU
of
the
biological
species
(
Waples
1991).
To
qualify
as
an
ESU
under
NMFS
policy,
a
salmon
population
or
group
of
populations
must
satisfy
the
following
two
criteria:
(
1)
it
must
be
substantially
reproductively
isolated
from
other
conspecific
population
units,
and
(
2)
it
must
contribute
substantially
to
ecological/
genetic
diversity
of
the
biological
species
as
a
whole
(
Waples
1991).
The
reproductive
isolation
need
not
be
absolute
but
must
be
strong
enough
to
permit
evolutionarily
important
differences
to
accrue
in
different
population
units.

Summary
of
Events
Leading
to
the
Steelhead
Status
Review
The
NMFS'
decision
to
initiate
a
comprehensive
steelhead
(
Oncorhynchus
mykiss)
status
review
was
prompted
by
three
petitions,
culminating
in
the
agency's
proposal
to
list
10
steelhead
ESUs
as
threatened
or
endangered.
On
May
6,
1992,
NMFS
received
a
petition
from
the
Oregon
Natural
Resources
Council
and
10
co­
petitioners
to
list
Oregon's
Illinois
River
winter
steelhead
under
the
ESA.
The
NMFS
completed
a
status
review,
summarized
in
the
May
20,
1993,

Federal
Register
(
58
FR
29390),
and
concluded
that
the
Illinois
River
winter
steelhead
did
not
represent
a
"
species"
under
the
ESA.
At
the
same
time
however,
NMFS
initiated
a
status
review
of
coastal
steelhead
populations
to
identify
the
ESU
that
includes
Illinois
River
winter
steelhead.

This
status
review
resulted
in
the
identification
of
a
Klamath
Mountains
Province
ESU
that
includes
steelhead
from
the
Illinois
River;
NMFS
proposed
listing
this
ESU
on
March
16,
1995
(
59
FR
14253).
The
NMFS
received
a
second
petition
on
September
21,
1993,
from
Washington
Trout
which
requested
listing
Washington's
Deer
Creek
summer
steelhead.
As
was
the
case
with
Illinois
River
winter
steelhead,
NMFS
determined
that
Deer
Creek
summer
steelhead
did
not
themselves
constitute
an
ESU
(
November
21,
1994,
59
FR
59981).
The
third
and
most
recent
steelhead
petition
was
submitted
by
Oregon
Natural
Resources
Council
and
15
co­
petitioners
on
February
16,
1994.
In
accepting
this
petition,
which
requested
ESA
listing
for
all
steelhead
in
Washington,
Oregon,
California
and
Idaho,
NMFS
announced
that
the
agency's
ongoing
steelhead
status
review
would
be
further
expanded
to
include
steelhead
populations
in
7
16
U.
S.
C.
§
1533
(
a)
(
1)
1994.

3
Idaho
(
May
27,
1994,
59
FR
27527).

On
August
9,
1996,
NMFS
published
in
the
Federal
Register
(
61
FR
41541)
its
initial
findings
on
a
comprehensive
status
review
of
West
Coast
steelhead
populations
in
Washington,
Oregon,

Idaho,
and
California.
The
NMFS
identified
15
ESUs
within
this
range,
and
proposed
to
list
5
ESUs
as
endangered
and
5
ESUs
as
threatened
under
the
ESA.
The
endangered
steelhead
ESUs
are
located
in
California
(
Central
California
Coast,
South/
Central
California
Coast,
Southern
California,
and
Central
Valley
ESUs)
and
Washington
(
Upper
Columbia
River
ESU).
The
threatened
steelhead
ESUs
are
dispersed
throughout
all
four
states
and
include
the
Snake
River
Basin,
Lower
Columbia
River,
Oregon
Coast,
Klamath
Mountains
Province,
and
Northern
California
ESUs.
Additionally,
NMFS
designated
the
Middle
Columbia
River
ESU
as
a
candidate
species
because
while
there
was
not
sufficient
information
available
to
indicate
that
steelhead
in
this
ESU
warrant
protection
under
the
ESA,
NMFS
identified
specific
risk
factors
and
concerns
that
need
to
be
evaluated
prior
to
concluding
its
assessment
of
the
overall
health
of
Middle
Columbia
River
steelhead.

Purpose
of
Report
In
accordance
with
the
ESA7,
NMFS
is
authorized
to
list
a
species
as
endangered
or
threatened
based
upon
any
one
or
more
of
the
five
following
factors:
(
A)
the
present
or
threatened
destruction,
modification,
or
curtailment
of
a
species'
habitat
or
range;

(
B)
overutilization
for
commercial,
recreational,
scientific,
or
educational
purposes;

(
C)
disease
or
predation;
(
D)
the
inadequacy
of
existing
regulatory
mechanisms;
or
(
E)
other
natural
or
manmade
factors
affecting
the
species
continued
existence.
The
purpose
of
this
report
is
to
synthesize
available
scientific
information
with
respect
to
the
factors
of
decline
for
west
coast
steelhead.
This
information
will
be
used
by
NMFS
in
making
its
listing
determinations
for
west
coast
steelhead.

To
ensure
that
the
best
available
information
was
used
in
this
report,
NMFS
solicited
the
8
50
C.
F.
R.
§
424.11
(
f)
1995.

4
assistance
of
state
and
tribal
fisheries
agencies
in
identifying
factors
of
decline
for
steelhead.

This
report
is
in
part
derived
from
information
provided
by
these
steelhead
co­
managers.
While
every
attempt
was
made
to
capture
the
most
up­
to­
date
information
on
steelhead
factors
for
decline,
NMFS
recognizes
that
some
areas
may
have
been
overlooked
or
not
dealt
with
in
sufficient
detail.
The
NMFS
encourages
anyone
interested
in
providing
comments
on
this
report
to
submit
materials
to
NMFS
at
the
addresses
below.

In
addition
to
consideration
of
the
factors
of
decline,
the
ESA
provides
that
NMFS
make
listing
determinations
"
after
taking
into
account
those
efforts,
if
any,
being
made
by
any
State
or
foreign
nation,
or
any
political
subdivision
of
a
State
or
foreign
nation
to
protect
such
species."
8
Toward
this
end,
NMFS
has
prepared
a
separate
document
entitled
Conservation
Measures:
A
supplement
to
the
notice
of
determination
for
west
coast
steelhead
which
addresses
Federal,

state,
tribal,
and
local
conservation
measures
pertinent
to
steelhead.
The
Conservation
Measures
report,
in
conjunction
with
this
report
and
NMFS'
Status
Review
of
West
Coast
Steelhead
(
Busby
et
al.
1996),
serve
as
the
basis
for
NMFS
steelhead
listing
determinations.
For
copies
of
these
or
other
related
documents,
write
to
Garth
Griffin,
NMFS,
Protected
Species
Branch,
525
NE
Oregon
St.
­
Suite
500,
Portland,
Oregon,
97232;
or
Craig
Wingert,
NMFS,

Protected
Species
Management
Division,
501
W.
Ocean
Blvd.
­
Suite
4200,
Long
Beach,
CA
90802.
5
6
Factors
Contributing
to
the
Decline
of
Steelhead
I.
The
Present
or
Threatened
Destruction,
Modification,
or
Curtailment
of
Steelhead
Habitat
or
Range.

A.
Hydropower
Development
Hydroelectric
development
has
impacted
fish
stocks
in
a
variety
of
ways.
Construction
of
dams
has
blocked
access
to
miles
of
previously
productive
habitat.
Modification
of
natural
flow
regimes
by
dams
has
resulted
in
increased
water
temperatures,
changes
in
fish
community
structure,
and
increased
travel
time
by
migrating
adult
and
juvenile
salmonids.
Physical
features
of
dams
such
as
turbines,
have
resulted
in
increased
mortality
of
adults
and
juvenile
salmonids
as
well.
Attempts
to
mitigate
adverse
impacts
of
these
structures
have
to
date
met
with
limited
success.

Hydroelectric
development
has
substantially
reduced
the
abundance
of
salmon
in
the
Columbia
River
Basin
and
the
Pacific
Northwest.
The
Northwest
Power
Planning
Council
(
NWPPC)
has
estimated
that
current
annual
salmon
and
steelhead
production
in
the
Columbia
River
Basin
is
more
than
10
million
fish
below
historical
levels,
with
8
million
of
this
annual
loss
attributable
to
hydropower
development
and
operation
(
Northwest
Power
Planning
Council
1987).

Approximately
half
of
the
8
million
fish
loss
resulted
from
curtailment
of
the
fishes
range
caused
by
Chief
Joseph
and
Hells
Canyon
dams
in
the
upper
Columbia
and
Snake
rivers,
respectively.

The
remaining
4
million
fish
loss
was
attributed
to
ongoing
annual
passage
losses
at
and
between
the
mainstem
projects
below
Chief
Joseph
and
Hells
Canyon
dams.
Although
the
specific
number
of
steelhead
lost
is
unknown,
they
are
included
in
the
overall
numbers
presented
by
the
NWPPC.

In
California,
as
in
the
Pacific
Northwest,
dams
which
have
been
constructed
on
many
rivers
and
streams
have
adversely
impacted
anadromous
salmonid
populations,
in
particular,
steelhead.

Most
hydroelectric
development
projects
in
California
have
not
been
required
to
construct
fish
bypass
facilities;
further,
projects
that
have
been
required
to
provide
fish
passage
have
met
with
limited
success.
Dams,
such
as
Copco
Dam
on
the
Klamath
River,
Scott
Dam
on
the
Eel
River,

Shasta
Dam
on
the
Sacramento
River,
Friant
Dam
on
the
San
Joaquin
River,
Folsom
Dam
on
7
the
American
River,
Oroville
Dam
on
the
Feather
River,
Warm
Springs
Dam
and
Coyote
Dam
on
Russian
River
system,
Los
Padres
Dam
on
the
Carmel
River,
Bradbury
Dam
on
the
Santa
Ynez
River,
Robles,
Casitas
and
Matilija
dams
in
the
Ventura
River
system,
the
Vern
Freeman
Diversion
Facility
on
the
Santa
Clara
River,
Rindge
Dam
on
Malibu
Creek
and
numerous
other
developments
throughout
California's
Central
Valley
and
coastal
rivers,
have
eliminated
or
severely
hindered
access
to
historical
spawning
and
rearing
habitats
and
have
altered
the
natural
flow
regimes
within
the
basins.

Juvenile
and
adult
steelhead
tend
to
experience
different
types
of
direct
and
indirect
physical
impacts
as
a
result
of
dam
configuration
and
operation.
Below
we
discuss
how
these
two
life
stages
are
impacted.

1.
Juvenile
Steelhead
Passage
Juvenile
steelhead
are
subject
to
increased
mortality
from
passage
through
dam
structures
and
environmental
conditions
created
by
dams
such
as
decreased
flow,
increased
water
temperatures,
and
changes
in
fish
community
structure.
Sublethal
impacts
(
e.
g.,
stress,
injury,

descaling,
and
delay)
also
occur
and
can
affect
survival
(
Hawkes
et
al.
1991;
Johnsen
et
al.

1990).

At
dams,
injury
and
mortality
can
occur
through
all
routes
of
passage
(
i.
e.,
turbines,
ice
and
trash
sluiceways,
juvenile
bypass
systems,
adult
fish
ladders);
however,
studies
have
documented
that
mortalities
through
turbines
are
generally
higher
relative
to
other
routes
of
passage.
Two
studies
using
subyearling
fall
chinook
salmon
Oncorhynchus
tshawytscha
showed
mean
turbine
mortalities
of
11
to
15
percent
(
Holmes
1952;
Schoeneman
et
al.
1961).

Screens
that
deflect
a
percentage
of
juvenile
steelhead
out
of
turbine
intakes
and
through
juvenile
bypass
facilities
have
been
installed
at
five
of
the
eight
mainstem
Columbia
River
dams
through
which
juvenile
steelhead
must
pass.
Juvenile
bypass
mortalities,
excluding
outfall
mortality,
are
believed
to
be
in
the
range
of
1
to
3
percent
(
Brege
et
al.
1987;
Ledgerwood
et
al.

1990;
Monk
and
Williams
1991).
8
At
dams
without
screened
bypass
systems,
limited
spill
is
provided
on
an
interim
basis
to
decrease
the
number
of
juvenile
fish
passing
through
turbines.
Spill
mortalities
have
been
estimated
in
the
range
of
0
to
3
percent
at
each
Columbia
River
hydroelectric
project,
though
estimated
mortality
was
higher
at
some
projects
prior
to
the
implementation
of
measures
to
control
dissolved
gas
supersaturation
(
Columbia
Basin
Fish
and
Wildlife
Authority
1988).

In
reservoirs,
the
loss
of
juvenile
migrants
is
related
to
a
number
of
factors.
Low
flows
during
outmigration
tend
to
make
juveniles
more
suspectable
to
predation
due
to
decreased
turbidity
and
increased
time
in
the
river.
High
water
temperatures
during
the
juvenile
steelhead
migration,
which
tend
to
be
associated
with
low
flows,
also
impair
steelhead
avoidance
of
predators.

Mortality
of
juvenile
steelhead
at
dams
and
in
reservoirs
may
be
substantially
reduced
by
collecting
juvenile
fish
at
upper
river
dams,
transporting
them,
and
releasing
them
below
the
lowest
dam.
For
example,
studies
using
primarily
Columbia
River
summer
and
fall
chinook
salmon
have
estimated
that
subyearling
fall
chinook
salmon
survival
for
fish
transported
from
McNary
Dam
to
below
Bonneville
Dam
was
more
than
1.8
times
higher
than
for
fish
migrating
inriver
(
Matthews
et
al.
1988).

2.
Adult
Steelhead
Passage.

Cumulative
passage
losses
for
adult
steelhead
passing
through
dams
may
be
high.
From
analyses
of
adult
salmon
counts
in
the
Columbia
and
Snake
Rivers,
it
has
been
estimated
that
upstream
passage
results
in
3
to
5
percent
mortality
to
adult
salmonids
(
Northwest
Power
Planning
Council
1986).
However,
this
fails
to
account
for
an
additional
unexplained
5
percent
mortality
which
may
result
from
delayed
mortality
or
possibly
poaching
(
Kaczynski
and
Palmisano
1993).
Based
on
these
figures,
mortality
may
range
from
5
to
10
percent
loss
per
hydroelectric
project
on
the
Columbia
and
Snake
rivers
systems
(
Kaczynski
and
Palmisano
1993).
There
were
no
estimates
available
for
steelhead
mortalities
associated
with
California
projects.
9
Delay
at
dams
is
an
important
factor
in
the
survival
of
adult
steelhead.
Factors
influencing
delay
include
the
effectiveness
of
fish
passage
facilities,
powerhouse
and
spillway
operations,
and
flow
and
water
quality.
Average
delay
at
lower
Columbia
River
mainstem
dams
may
be
one
to
three
days
when
good
passage
conditions
exist
(
Ross
1983).
Delay
is
important
because
adult
steelhead
do
not
generally
feed
during
their
upstream
migration.
Delays
during
migration
deplete
limited
energy
reserves,
which
can
reduce
survival
and
spawning
success.

Delay
can
be
greater
when
adult
passage
facilities
are
not
operated
in
conformance
with
established
criteria
(
i.
e.,
when
reduced
hydraulic
head
and
weir
depths
reduce
attraction
flows
at
fishway
entrances).
Inadequate
water
velocity
inside
fishways
also
increases
delay.
Adult
fishways,
on
mainstem
Columbia
River
dams,
have
operated
below
flow/
velocity
criteria
in
one
or
more
areas
of
the
fishways
frequently
a
substantial
amount
of
time
(
Fish
Passage
Center
of
the
Columbia
Basin
Fish
and
Wildlife
Authority
1988,
1989,
1990).

Another
important
factor
to
consider
regarding
steelhead
passage
is
the
potential
of
"
fall
back"

of
migrating
adults
through
turbine
structures.
Research
has
indicated
that
mortality
rates
for
steelhead
that
fall
back
through
turbines
may
range
from
22
to
41
percent
(
Wagner
and
Ingram
1973).
This
may
be
an
important
source
of
mortality
for
migrating
steelhead,
however,
it
has
been
difficult
to
quantify
the
degree
to
which
this
has
affected
steelhead
coastwide.

In
summary,
hydroelectric
development
and
dam
operations
have
to
a
large
degree
modified
and
curtailed
steelhead
habitat
and
range.
Dam
structures
through
which
migrating
steelhead
are
able
to
pass
often
contribute
to
increased
mortality
through
physical
injury
and
delay.
Measures
implemented
to
date
have
failed
to
effectively
mitigate
these
impacts.

B.
Water
Withdrawal,
Conveyance,
Storage,
and
Flood
Control
Depletion
and
storage
of
natural
flows
have
drastically
altered
natural
hydrological
cycles
in
the
Snake
and
Columbia
River
Basins,
as
well
as
many
rivers
and
streams
in
Washington,
Oregon,

Idaho
and
California.
Alteration
of
streamflows
has
resulted
in
juvenile
salmonid
mortality
for
a
variety
of
reasons:
migration
delay
resulting
from
insufficient
flows
or
habitat
blockages;
loss
of
10
sufficient
habitat
due
to
dewatering
and
blockage;
stranding
of
fish
resulting
from
rapid
flow
fluctuations;
entrainment
of
juveniles
into
poorly
screened
or
unscreened
diversions;
and
increased
juvenile
mortality
resulting
from
increased
water
temperatures
(
Bergren
and
Filardo
1991;
California
Advisory
Committee
on
Salmon
and
Steelhead
Trout
1988;
California
Department
of
Fish
and
Game
1991;
Columbia
Basin
Fish
and
Wildlife
Authority
1991a;

Chapman
et
al.
1994;
Cramer
et
al.
1995;
Palmisano
et
al.
1993;
Reynolds
et
al.
1993).
In
addition
to
these
factors,
reduced
flows
negatively
affect
fish
habitats
due
to
increased
deposition
of
fine
sediments
in
spawning
gravels,
decreased
recruitment
of
new
spawning
gravels,
and
encroachment
of
riparian
and
non­
endemic
vegetation
into
spawning
and
rearing
areas
resulting
in
reduced
available
habitat.

Within
the
Columbia
and
Snake
rivers
systems,
the
largest
consumptive
use
of
water
is
agricultural
irrigation.
In
addition
to
direct
diversion
of
natural
flows,
agricultural
water
use
promotes
and
is
supported
by
water
storage
in
Federal
and
private
reservoirs.
For
example,

total
discharge
of
the
Snake
River
on
an
annual
basis
is
approximately
36
million
acre­
feet
(

MAft
(
44.4
cubic
kilometers
(
km3)).
Of
this,
approximately
16
MA­
ft
(
19.73
km3)
is
diverted
annually,
and
6
MA­
ft
(
7.4
km3)
is
consumed
by
agriculture
(
Hydrosphere
1991).
Additionally,

total
active
storage
(
the
amount
of
water
that
can
be
removed
from
a
reservoir)
in
the
Snake
River
Basin
above
Hells
Canyon
Dam
(
including
Brownlee
Reservoir)
is
approximately
11.3
MA­
ft
(
13.94
km3).
The
amount
of
active
storage
available
for
use
varies
from
year
to
year
depending
on
run­
off
and
rainfall.
This
storage
alters
timing
of
peak
flows
in
the
Snake
River,

that
would
under
natural
conditions,
have
occurred
during
the
spring/
summer
run­
off,
when
juvenile
salmonids
are
migrating.

In
California,
water
withdrawal,
conveyance
and
diversion
has
resulted
in
the
loss
of
a
significant
amount
of
steelhead
habitat.
Diversion
and
transfer
of
water
has
resulted
in
depleted
river
flows
necessary
for
migration,
spawning,
rearing,
flushing
of
sediment
from
the
spawning
gravels,

gravel
recruitment
and
transport
of
large
woody
debris
(
Botkin
et
al.
1995;
California
Advisory
Committee
on
Salmon
and
Steelhead
Trout
1988;
Reynolds
et
al.
1993).
11
There
are
roughly
1,400
Federal,
state,
and
private
dams
in
California
at
least
25
feet
(
7.5
meters)
high
or
holding
back
a
minimum
of
50
acre­
feet
(
A­
ft)
(
0.06
cubic
meters
(
m3))
of
water
(
California
Department
of
Water
Resources
1982a).
One
hundred
and
one
of
these
dams
contain
90
percent
of
the
total
capacity
of
all
California
dams.
Including
dams
on
the
Colorado
River,
these
dams
collectively
can
impound
42.2
MA­
ft
(
51.8
km3)
of
water.
Titus
et
al.
(
1994)

extensively
reviewed
current
freshwater
habitat
conditions
for
steelhead
populations
along
the
California
coast
south
of
San
Francisco
Bay.
They
reported
blockages
in
12
of
46
tributaries
within
the
southern
portion
of
the
central
California
ESU,
blockages
in
28
of
66
tributaries
within
the
south­
central
California
coast
ESU,
and
that
of
32
tributaries
within
the
southern
California
ESU,
21
have
blockages
due
to
dams
and
29
have
impaired
mainstem
passage.

Recent
drought
conditions
which
persisted
from
the
mid­
1980'
s
through
the
early
1990'
s
have
shown
that
there
is
little
water
to
spare
for
instream
uses
in
many
areas
of
California.

The
Sacramento
River
Basin
covers
an
area
in
excess
of
22,000
square
miles
(
57,000
square
km)
in
central
and
northeastern
California
and
is
the
largest
river
system
in
California.
Salmon
and
steelhead
spawning
and
rearing
habitat
of
the
Central
Valley
of
California
has
been
reduced
from
approximately
6,000
miles
(
9,677
km)
that
existed
prior
to
the
construction
of
dams
to
less
than
300
miles
(
484
km)
today,
a
95
percent
reduction
in
available
habitat
(
California
Advisory
Committee
on
Salmon
and
Steelhead
Trout
1988;
Reynolds
et
al.
1993).
However,
because
steelhead
utilize
habitats
located
in
the
upper
tributaries
of
watersheds,
and
virtually
all
of
the
major
dams
were
built
in
the
lower
reaches
of
the
rivers,
there
is
probably
a
greater
reduction
in
available
habitat
for
steelhead
populations.

The
operations
of
the
Central
Valley
Project
(
CVP)
and
the
State
Water
Project
­
Harvey
O.

Banks
Pumping
Plant
(
SWP)
in
the
Sacramento­
San
Joaquin
delta
region
have
had
a
tremendous
negative
effect
on
steelhead.
The
CVP
and
SWP
cause
reverse
flows
in
the
delta
region
which
delay
migration
of
juvenile
and
adult
steelhead,
entrain
fish
into
the
pumping
facilities,
and
increase
predation
at
water
facilities
(
California
Department
of
Fish
and
Game
1991;
Reynolds
et
al.
1993).
The
SWP
and
the
California
Aqueduct
more
than
doubled
the
capacity
to
export
water
south
to
southern
California.
Prior
to
the
installation
and
operation
of
the
SWP
Delta
12
Pumps,
Delta
water
exports
were
limited
to
the
quantities
the
Federal
pumps
could
deliver.
The
addition
of
the
SWP
delta
pumps,
the
magnitude
of
reverse
flows
across
the
delta
increased,

delta
outflow
decreased,
and
the
concomitant
entrainment
of
salmonids
increased
(
Reynolds
et
al.
1993).
Many
of
the
salmonid
populations
in
the
Central
Valley
showed
a
dramatic
decrease
in
abundance
when
the
SWP
came
online.

Water
development
and
flood
control
projects
have
dramatically
altered
the
Sacramento
and
San
Joaquin
rivers'
natural
flow
regimes
and
sediment
transport
characteristics.
The
rivers
of
the
Central
Valley
are
now
managed,
unnatural
waterways
and
are
operated
to
make
daily
deliveries
to
irrigation
districts
and
to
prevent
flooding
(
California
Advisory
Committee
on
Salmon
and
Steelhead
Trout
1988).
These
projects
have
also
had
a
major
influence
on
the
lower
reaches
of
the
river
and
its
associated
riparian
habitat
(
see
loss
of
riparian
vegetation,
section
1.
c).

Federaland
state­
funded
structures
in
the
Sacramento­
San
Joaquin
Valley
include
Shasta
and
Keswick
dams,
and
the
Red
Bluff
Diversion
Dam
all
in
the
upper
Sacramento
River,
Whiskeytown
Reservoir
which
stores
and
diverts
water
from
the
Trinity
River
into
the
Sacramento
River,

Folsom
Dam
on
the
American
River,
Oroville
Dam
on
the
Feather
River,
Don
Pedro
Dam
on
the
Tuolumne
River,
New
Melones
on
the
Stanislaus
River,
Friant
Dam
on
the
San
Joaquin
River,

Exchequer
Dam
on
the
Merced
River,
the
SWP,
and
the
Tracey
Pumping
Plant
(
CVP).
These
structures
cumulatively
have
had
an
enormous
negative
impact
on
all
anadromous
salmonid
populations
(
Moyle
and
Herbold
1989).
The
rivers
in
the
Sacramento
and
San
Joaquin
systems
are
regulated
to
the
point
that
high
flows
below
the
dams
typically
occur
in
late
spring
and
summer
during
the
irrigation
season,
and
low
flows
occur
in
the
fall,
winter,
and
early
spring
during
the
storage
season
(
Reynolds
et
al.
1993).
This
flow
regime
is
completely
inverse
to
the
conditions
in
which
salmonids
evolved
in
the
Central
Valley.

Flood
control
operations
at
dams
can
also
conflict
with
efforts
to
provide
migration
flows
for
juvenile
steelhead
(
Hydrosphere
1991).
Flood
control
constraints
at
Brownlee
Reservoir
on
the
Snake
River,
Idaho,
require
that
500,000
AF
(
0.62
km3)
of
storage
be
available
by
the
end
of
February,
and,
if
necessary,
all
980,000
AF
(
1.20
km3)
of
active
storage
can
be
evacuated
(
Bennett
et
al.
1979).
Thus,
water
that
could
be
used
to
aid
anadromous
fish
migration
is
13
drafted
prior
to
the
migration
period.
Flood
control
constraints
at
Dworshak
Reservoir
on
the
Snake
River
have
a
similar
effect
on
availability
of
water
for
juvenile
salmonid
migration.

Adding
to
the
problem
is
the
inclination
toward
increased
production
of
hydropower
at
both
projects
during
the
winter
(
Hydrosphere
1991).

The
Sacramento
River
Flood
Control
Project
extends
south
from
Chico
Landing
and
includes
a
series
of
levees,
weirs,
and
overflow
channels.
The
Sacramento
River
Bank
Protection
Project
was
designed
to
protect
the
flood
control
system
between
Chico
Landing
and
Collinsville;
today
over
150
miles
(
242
km)
of
the
Sacramento
River's
banks
have
been
riprapped
(
California
State
Land
Commission
1993).
The
Chico
Landing
to
Red
Bluff
Comprehensive
Bank
Stabilization
Project
was
designed
to
control
lateral
migration
of
the
river
in
this
reach
and
is
about
54
percent
complete
(
Reynolds
et
al.
1993).

Flood
control
operations
at
the
Folsom
Reservoir
on
the
American
River
have
also
impacted
steelhead
populations.
On
several
occasions
releases
from
the
reservoir
have
been
abruptly
reduced
resulting
in
excessive
mortality
of
naturally­
produced
juvenile
salmonids.
In
the
spring
of
1995,
flows
were
reduced
from
18,000
to
8,000
cubic
feet
per
second
(
cfs)
in
a
four­
hour
period,
resulting
in
the
loss
of
several
hundred
thousand
salmon,
steelhead,
and
other
juvenile
fishes
(
California
Department
of
Fish
and
Game
1995).

From
this,
it
can
be
concluded
that
water
diversion,
conveyance,
withdrawal,
and
storage
for
agriculture,
industrial,
and
municipal
uses
have
drastically
altered
the
natural
flow
regimes
throughout
the
range
of
steelhead.
This
has
resulted
in
decreased
juvenile
and
adult
steelhead
survival
during
migration,
and
in
many
cases,
had
resulted
in
the
dewatering
and
loss
of
important
spawning
and
rearing
habitats.

C.
Land
use
activities
High
water
quality
and
quantity
are
essential
for
survival,
growth,
reproduction,
and
migration
of
individuals
composing
aquatic
and
riparian
communities.
Important
water
quality
elements
for
aquatic
organisms
include
water
temperatures
within
the
migratory
range,
rearing
and
14
emergence
needs
of
fish
and
other
aquatic
organisms
(
Quinn
and
Tallman
1987;
Sweeney
and
Vannote
1978).
Desired
conditions
for
salmonids
include
an
annual
abundance
of
cool
(
generally
less
than
68
E
Fahrenheit
(
F)
(
20
E
Celsius
(
C)),
well
oxygenated
water,
low
suspended
sediments
(
Barnhart
1986;
Sullivan
et
al.
1987)
and
other
pollutants
that
could
limit
primary
production
and
benthic
invertebrate
abundance
and
diversity
(
Cordone
and
Kelley
1961;
Lloyd
et
al.
1987).

Numerous
studies
have
been
conducted
regarding
the
impacts
of
land
use
activities
on
salmonid
habitat
in
the
states
of
Washington,
Oregon,
Idaho,
and
California.
Land
use
activities
associated
with
logging,
road
construction,
urban
development,
mining,
agriculture,
and
recreation
have
significantly
altered
fish
habitat
quantity
and
quality.
Associated
impacts
of
these
activities
include
the
following:
alteration
of
streambank
and
channel
morphology;

alteration
of
ambient
stream
water
temperatures;
degradation
of
water
quality;
elimination
of
spawning
and
rearing
habitat,
fragmentation
of
available
habitats;
elimination
of
downstream
recruitment
of
spawning
gravels
and
large
woody
debris;
removal
of
riparian
vegetation
resulting
in
increased
stream
bank
erosion;
and
degradation
of
water
quality
(
Botkin
et
al.
1995;
Bottom
et
al.
1985;
Brown
et
al.
1994;
Bryant
1994;
California
Advisory
Committee
on
Salmon
and
Steelhead
Trout
1988;
California
Department
of
Fish
and
Game
1965,
1991,
1994;
California
State
Lands
Commission
1993;
McEwan
and
Jackson
1996;
Nehlsen
et
al.
1991;
Titus
et
al.
in
prep.;
Wilderness
Society
1993).
The
loss
of
channel
complexity,
pool
habitat,
suitable
gravel
substrate,
and
large
woody
debris,
and
other
development
activities
have
caused
increased
sediment
input
into
spawning
and
rearing
areas
(
Bottom
et
al.
1985,
Forest
Ecosystem
Management
Assessment
Team
1993,
Higgins
et
al.
1992,
U.
S.
Forest
Service
and
U.
S.
Bureau
of
Land
Management
1994a).

1.
Logging
and
Agricultural
Activities
Research
indicates
that
activities
associated
with
logging
result
in
habitat
simplification
of
stream
channels
through
sedimentation,
channelization,
and
loss
of
riparian
vegetation,
large
woody
debris,
and
habitat
complexity
(
Anderson
1971;
Bottom
et
al.
1985;
U.
S.
Forest
Service
and
U.
S.
Bureau
of
Land
Management
1994b;
Wilderness
Society
1993).
Further,
historical
15
practices,
such
as
splash
dams,
and
wide
spread
removal
of
beaver
dams,
log
jams
and
snags
from
river
channels,
have
adversely
modified
fish
habitat
(
Bottom
et
al.
1985).
More
recently,

logging
has
reduced
the
amount
of
instream,
large
woody
debris,
resulting
in
significant
impacts
to
salmonid
habitat.

Agricultural
practices
have
also
contributed
to
the
degradation
of
salmonid
habitat
on
the
West
Coast
through
irrigation
diversions,
overgrazing
in
riparian
areas,
and
compaction
of
soils
in
upland
areas
from
livestock
(
Botkin
et
al.
1995;
Palmisano
et
al.
1993).
Grazing
has
been
identified
by
Bottom
et
al.
(
1985)
as
having
the
foremost
impact
on
riparian
vegetation
in
Oregon
streams.
Livestock
grazing
patterns
in
and
around
riparian
areas
can
alter
the
vigor,

composition,
and
diversity
of
natural
vegetation.
This
in
turn
can
affect
the
site's
ability
to
control
erosion,
provide
stability
to
stream
banks,
and
provide
shade,
cover,
and
nutrients
to
the
stream.
Mechanical
compaction
can
reduce
the
productivity
of
the
soils
and
cause
bank
slough
and
erosion.
Mechanical
bank
damage
often
leads
to
channel
widening,
lateral
stream
migration
and
excess
sedimentation.

Both
logging
and
agriculture
activities
result
in
many
similar
impacts
on
salmonid
habitat.
Major
impacts
common
to
both
activities
include
loss
of
large
woody
debris,
sedimentation,
loss
of
riparian
(
streamside)
vegetation,
and
loss
of
habitat
complexity,
all
of
which
affect
water
quality
and
the
biotic
communities.
Summarized
below
are
the
effects
of
these
activities
on
steelhead
and
their
habitat.

a.
Loss
of
Large
Woody
Debris
Large
quantities
of
downed
trees
are
a
functionally
important
component
of
many
streams
and
estuaries
(
Naiman
et
al.
1992;
Sedell
and
Luchessa
1982;
Sedell
and
Maser
1994;
Swanson
et
al.

1976).
Large
woody
debris
influences
channel
morphology
by
affecting
longitudinal
profile,

pool
formation,
channel
pattern
and
position,
and
channel
geometry
(
Bisson
et
al.
1987).

Downstream
transport
rates
of
sediment
and
organic
matter
are
controlled
in
part
by
storage
of
this
material
behind
large
wood
(
Betscha
1979).
Large
wood
affects
the
formation
and
16
distribution
of
habitat
units,
provides
cover
and
complexity,
and
acts
as
a
substrate
for
biological
activity
(
Bisson
et
al.
1987;
Sedell
and
Maser
1994;
Swanson
et
al.
1976).
Wood
enters
streams
inhabited
by
salmonids
either
directly
from
adjacent
riparian
zones
or
from
riparian
zones
in
adjacent
non­
fish
bearing
tributaries.

Prior
to
the
1970'
s,
there
was
so
much
debris
resulting
from
poor
logging
practices
that
many
streams
were
completely
clogged
and
were
thought
to
have
been
total
barriers
to
fish
migration.

As
a
result,
in
the
1960'
s
and
early
1970'
s
it
was
common
practice
among
fishery
management
agencies
to
remove
woody
debris
thought
to
be
a
barrier
to
fish
migration
(
Bisson
and
Sedell
1984).
However,
it
is
now
recognized
that
too
much
large
woody
debris
was
removed
from
the
streams
resulting
in
a
loss
of
salmonid
habitat
(
Bottom
et
al.
1985,
California
Department
of
Fish
and
Game
1994).
Botkin
et
al.
(
1995)
reported
that
the
routine,
large
scale
removal
of
woody
debris
prior
to
1980
had
major,
long­
term
negative
effects
on
rearing
habitats
for
salmonids
in
southern
Oregon
and
northern
California.
Areas
that
were
subjected
to
this
removal
of
large
woody
debris
are
still
limited
in
the
recovery
of
salmonid
stocks;
this
limitation
could
be
expected
to
persist
for
50
to
100
years
following
removal
of
debris.
Botkin
et
al.

(
1995)
also
stated
that
a
primary
goal
in
salmonid
ecosystem
recovery
would
be
correcting
the
insufficient
amount
or
loss
of
large
woody
debris.
Botkin
et
al.
(
1995)
further
stated
that
the
most
important
element
of
woody
debris
are
large,
decay­
resistant
conifers.

Past
and
present
harvesting
practices
have
eliminated
large
trees,
large
logs,
and
other
woody
debris
from
streamside
areas
which
could
have
otherwise
been
recruited
to
the
channel.

Kreissman
(
1991)
reported
that
California
had
lost
89
percent
of
the
state's
riparian
woodland.

There
has
been
an
83
to
90
percent
loss
of
old­
growth
forests
in
Douglas
Fir
regions
of
Oregon
and
Washington
(
Harris
1984;
Norse
1990;
Spies
and
Franklin
1988).
Kellogg
(
1992)
reported
that
96
and
75
percent
of
the
original
coastal
temperate
rainforests
in
Oregon
and
Washington,

respectively,
have
been
logged.
This
is
particularly
a
problem
for
redwood,
which
takes
many
decades
to
decay
and
could
have
provided
long
term
benefits
to
fish
habitat
and
watershed
stability.
Wilburn
(
1985)
reported
that
California
had
lost
greater
than
85
percent
of
its
coastal
redwood
Sequoia
sempervirens
forests
by
the
early
1980'
s.
Repeated
entries
into
the
riparian
17
zones
for
sanitation
salvage
and
harvesting
under
exemptions
and
emergency
notices
continue
to
further
limit
recruitment
of
large
woody
debris
(
Bisson
et
al.
1987;
Bryant
1980;
California
Department
of
Fish
and
Game
1994).
Consequently,
there
is
now
very
little
recruitment
of
large
or
other
woody
debris
in
most
coastal
streams
needed
to
replace
old
logs
that
have
been
washed
out
of
the
system,
buried
during
flood
events,
or
removed
decades
ago
to
provide
fish
passage.

Bottom
et
al.
(
1985)
and
Seddell
et
al.
(
1988)
reported
that
large
logs
are
no
longer
available
to
replace
old
logs
that
are
still
buried
in
some
stream
reaches
due
to
logging
in
stream
side
areas.

b.
Sedimentation
The
U.
S.
Environmental
Protection
Agency
reporting
the
results
of
its
assessments
found
many
streams
throughout
Washington,
Idaho,
Oregon,
and
California
to
be
either
moderately
or
severely
impacted
by
increases
in
water
temperature
and
sedimentation
(
Edwards
et
al.
1992).

Sedimentation
resulting
from
logging,
mining,
urban
and
agricultural
activities
is
a
primary
cause
of
habitat
degradation
in
the
range
of
steelhead.
Quantitatively,
sediment
has
been
identified
as
the
greatest
single
pollutant
in
the
nation's
waters
(
Barnhart
1986,
Poon
and
Garcia
1982,

Ritchie
1972,
U.
S.
Environmental
Protection
Agency
1988).
Suspended
solids
can
have
damaging
physical
and
biological
effects.
Cordone
and
Kelley
(
1961)
and
Herbert
and
Merkens
(
1961)
reported
that
suspended
sediment
occasionally
reaches
concentrations
high
enough
to
directly
injure
steelhead.
Sigler
et
al.
(
1984)
reported
that
chronic
turbidity
in
streams
during
emergence
and
rearing
of
steelhead
affects
the
numbers
and
quality
of
fish
production.
In
general,
effects
of
sedimentation
on
salmonids
are
well
documented
and
include:
clogging
and
abrasion
of
gills
and
other
respiratory
surfaces;
adhering
to
the
chorion
of
eggs;
providing
conditions
conducive
to
entry
and
persistence
of
disease­
related
organisms;
inducing
behavioral
modifications;
entombing
different
life
stages;
altering
water
chemistry
by
the
absorption
of
chemicals;
affecting
useable
habitat
by
scouring
and
filling
of
pools
and
riffles
and
changing
bedload
composition;
reducing
photosynthetic
growth
and
primary
production;
and
affecting
intergravel
permeability
and
dissolved
oxygen
levels
(
Koski
and
Walter
1978)
(
Appendix
A).

Increased
turbidity
decreases
photosynthesis
of
aquatic
plants
and
can
clog
the
respiratory
surfaces
and
feeding
mechanisms
of
aquatic
animals.
Turbidity
results
when
fine
silt,
part
of
the
18
overall
sediment
transport,
remains
suspended
for
long
periods
of
time.
Turbidity
causes
light
to
be
scattered
and
absorbed,
reducing
light
penetration
and
thus
diminishing
or
even
eliminating
aquatic
plant
growth.
Loss
of
aquatic
plants
leads
to
the
loss
of
associated
snails
and
aquatic
invertebrates
and
serve
as
a
food
source
for
young
fish.
Barnhart
(
1986)
reported
that
deposited
sediment
directly
reduces
the
carrying
capacity
of
the
stream
by
reducing
available
rearing
habitat;
indirectly,
sediments
reduce
the
production
of
invertebrate
food
resources
for
rearing
juvenile
steelhead.
The
authors
concluded
that
rearing
habitats
of
juvenile
salmonids
in
streams,

as
well
as
spawning
gravels,
require
protection
from
excessive
quantities
of
fine
sediments.

Chronic
turbidity
in
streams
was
shown
by
Sigler
et
al.
(
1984)
to
affect
the
number
and
quality
of
fish
produced.
Further,
high
concentrations
of
fine
sediment
were
demonstrated
by
Phillips
et
al.
(
1975)
to
result
in
premature
emergence
of
coho
salmon.
Turbidity
generally
reduces
feeding
by
fish
even
if
there
is
an
abundance
of
prey
(
Noggle
1978).
Some
salmonid
species
have
complex
reproductive
and
social
behaviors
that
depend
on
visual
signals
which
may
be
obscured
in
turbid
waters
(
Berg
and
Northcote
1985).

The
steelhead's
environment
can
be
impaired
by
particles
deposited
as
bedload
sediment.
Bjornn
et
al.
(
1977)
found
significant
reductions
in
the
numbers
of
juvenile
steelhead
in
stream
channels
where
boulders
were
embedded
in
sediment.
Embedded
sediment
also
decreases
the
ability
of
juvenile
steelhead
to
migrate
into
the
substrate
during
high
winter
flows
to
avoid
being
flushed
out
of
the
system.
Crouse
et
al.
(
1981)
reported
significant
decreases
in
fish
production
in
streams
where
cobbles
were
embedded
80­
100
percent
and
where
sediment
(
2.0
mm
or
less)

composed
26­
31
percent
(
by
volume)
of
the
total
substrate
composition.

Evidence
is
emerging
that
stability
of
spawning
gravels
may
be
a
critical
limiting
factor
for
salmonids.
Nawa
et
al.
(
1991)
found
that
scour
and
fill
of
aggraded
stream
beds
caused
by
minor
storms
(
two
year
events)
in
southwest
Oregon
was
sufficient
to
cause
mortality
of
salmonid
eggs
and
alevins.
Payne
and
Associates
(
1989)
reported
that
gravels
are
extremely
unstable
in
the
lower
Klamath
River
tributaries;
therefore,
mortality
of
eggs
similar
to
that
noted
by
Nawa
et
al.
(
1990)
is
likely
occurring
there.
California
Department
of
Water
Resources
(
1982b)
reported
that
decreasing
stability
of
spawning
gravels
due
to
aggradation
was
the
major
19
cause
of
declines
of
salmon
runs
in
the
South
Fork
Trinity
River.
Smith
(
1992)
reported
the
loss
of
several
salmon
redds
in
Waddell
Creek,
California,
due
to
late
winter
storm's
scouring
flows.

Sedimentation
has
also
been
shown
to
increase
stream
temperatures.
Hagans
et
al.
(
1986)

reported
water
temperatures
to
be
adversely
impacted
by
increased
sedimentation
of
gravels
and
pools.
This
impact
is
caused
by
(
1)
the
loss
of
a
reflective
bottom
with
darker
sediment
(
as
opposed
to
clean
gravels)
which
stores
and
transfers
heat
into
the
water
column
from
direct
solar
radiation;
and
(
2)
reduced
water
flow
through
interstitial
gravel
spaces
increases
exposure
of
the
water
column
to
direct
solar
radiation
and
thus
more
heat.

Logging
conducted
in
west
coast
watersheds
prior
to
the
early
1970'
s
induced
the
damage
described
above
to
many
coastal
streams.
Accelerated
rates
of
erosion
and
sedimentation
are
a
consequence
of
most
forest
land
management
activities.
Road
networks
in
many
upland
areas
of
the
Pacific
Northwest
are
the
most
important
source
of
management­
accelerated
sediment
delivery
to
anadromous
fish
habitats
(
Forest
Ecosystem
Management
Assessment
Team
1993).

The
sediment
contribution
to
streams
from
roads
is
often
much
greater
than
that
from
all
other
land
management
activities
combined
(
Gibbons
and
Salo
1973).
Federal
lands
(
Forest
Service
and
Bureau
of
Land
Management)
within
the
range
of
the
northern
spotted
owl
Stix
occidentalis
caurina
contain
approximately
110,000
miles
(
177,000
km)
of
road,
with
an
estimated
250,000
stream
crossings
(
e.
g.,
culverts,
wet
crossings)
in
the
road
network
(
Forest
Ecosystem
Management
Assessment
Team
1993).
Road
densities
on
private
lands
are
considered
to
be
higher.
Fisk
et
al.
(
1966)
provided
testimony
to
California's
State
Interim
Committee
on
Stream
and
Beach
Erosion
in
1956
and
indicated
that
over
1,000
miles
(
1,600
km)
of
streams
in
California
had
been
damaged
or
destroyed
by
1956.
In
1962,
Calhoun
and
Seeley
(
1963)
found
that
33
streams
totalling
about
55
miles
(
89
km)
were
damaged
that
year.
Fisk
et
al.
(
1966)

reported
that
surveys
on
the
Garcia
River
and
Redwood
Creek,
California,
showed
that
the
Garcia
River
was
severely
to
moderately
damaged
by
ongoing
logging
and
road
building
along
52
(
84
km)
of
104
miles
(
168
km)
of
available
salmonid
habitat
while
68.5
(
110
km)
of
84
miles
(
135
km)
of
habitat
in
Redwood
Creek
were
similarly
damaged.
Holman
and
Evan
(
1964)

estimated
all
of
the
70
miles
(
113
km)
of
potential
habitat
in
the
Noyo
River
during
the
late
20
1950s
had
been
damaged
by
past
logging
activities
prior
to
the
mid
1940s.
In
addition,
the
U.
S.

Bureau
of
Reclamation
(
1973)
surveyed
Redwood
Creek
in
Humblodt
County,
Ten
Mile,
and
Big
Rivers
in
Mendocino
County,
and
Gualala
River
in
Sonoma
County,
California,
and
found
that
all
had
been
negatively
affected
by
logging
activities,
road
building,
livestock
grazing,
or
urbanization.

Wetlands,
estuaries
and
lagoons
provide
critical
nursery
habitat
for
all
juvenile
salmonids
migrating
to
the
ocean
and
are
essential
to
all
anadromous
salmonids.
These
critical
habitats
play
an
important
role
as
a
feeding
area
for
juvenile
salmonids
and
also
in
their
acclimatization
to
higher
salinities
(
Cooper
and
Johnson
1992).
Loss
of
these
habitats
may
limit
food
resources
for
juvenile
salmonids.
Therefore,
juveniles
may
tend
to
migrate
to
open
water
at
a
smaller
size
and
thus
be
more
susceptible
to
predation
(
Thom
1991).
The
ocean
survival
for
juvenile
salmonids
is
greatly
increased
if
rearing
fish
are
able
to
attain
larger
size
for
an
extended
period
in
the
estuary
(
Simenstad
et
al.
1982).

The
Oregon
and
California
coasts
have
a
naturally
low
shoreline/
coastline
ratio
(
Bottom
et
al.

1986).
As
a
consequence,
there
are
few
well­
developed
estuaries
and
other
nearshore
rearing
areas.
Almost
all
of
the
west
coast
estuaries
and
wetlands
that
have
been
scrutinized
have
been
subject
to
significant
degradation.
These
habitats
are
subject
to
degradation
from
a
variety
of
causes
including
the
following:
diking,
filling,
erosion,
artificial
breaching,
chemical
pollution,

sewage
and
livestock
runoff,
and
water
withdrawals
(
surface
and
ground
water
extraction).

Busby
(
1991),
Hofstra
(
1983),
Puckett
(
1977),
and
Smith
(
1987,
1990)
reported
that
many
estuaries
remain
filled
with
sediment
and
debris
washed
in
from
upstream
areas
and
are
no
longer
capable
of
supporting
the
numbers
of
salmonid
juveniles
they
once
did.
Higgins
(
1991)

reported
that
species
diversity
dramatically
declined
in
the
Eel
River
estuary
and
that
the
estuary
decreased
considerably
in
size
between
1950
and
1977.
The
lack
of
habitat
in
estuaries
due
to
sedimentation
may
be
forcing
juvenile
salmonids
into
the
marine
environment
at
a
less
than
optimal
size
thus
reducing
their
ocean
survival
(
Nicholas
and
Hankin
1988b).

Variability
in
ocean
conditions
and
paucity
of
high
quality
near­
shore
habitats
makes
freshwater
21
environments
more
crucial
for
the
survival
and
persistence
of
steelhead
trout
in
the
southern
one­
half
of
the
steelhead
range.
Compared
to
northern
areas
with
more
stable
ocean
conditions
and
better
developed
near­
shore
habitats,
steelhead
in
the
southern
one­
half
of
their
range
are
more
dependent
on
freshwater
environments
to
achieve
larger
sizes,
which
increases
probability
of
marine
survival
(
Pearcy
1992;
Shapovalov
and
Taft
1954).

As
streams
and
pools
fill
in
with
sediment,
flood
flow
capacity
is
reduced
and
meandering
increases,
resulting
in
wider
and
shallower
streams
with
less
structure
and
undercut
banks.
Such
changes
cause
decreased
stream
stability
and
increased
bank
erosion
which
exacerbates
existing
sedimentation
problems.
All
of
these
sources
contribute
to
the
sedimentation
of
spawning
gravels
and
filling
of
pools,
wetlands
and
estuaries
used
by
all
anadromous
salmonids.
Although
steelhead
are
resilient
and
are
capable
of
tolerating
suspended
sediments
for
short
periods
of
time,
prolonged
exposure
to
high
sediment
levels
can
result
in
simplification
of
critical
habitats.

This
can
lead
to
starvation,
predation,
or
reproductive
failure
of
the
species.

c.
Loss
of
Riparian
Vegetation
Many
watersheds
in
the
range
of
west
coast
steelhead
have
been
subjected
to
land
use
activities
which
have
resulted
in
the
reduction
of
riparian
vegetation.
The
type
and
structure
of
streamside
vegetation
reflects
both
climate
and
the
disturbance
regime
of
the
area.
The
reduction
in
tree
shade
canopy
along
with
the
initial
and
continued
loss
of
trees
adjacent
to
riparian
zones
can
produce
significant
increases
in
water
temperatures
(
Bottom
et
al.
1985;
California
Department
of
Fish
and
Game
1994;
Forest
Ecosystem
Management
Assessment
Team
1993).
Riparian
vegetation
protects
stream
banks
from
erosion
through
soil
binding
by
root
masses
and
the
presence
of
ground
litter
and
dense
overstory
canopy,
which
impedes
the
rate
of
surface
runoff
(
Forest
Ecosystem
Management
Assessment
Team
1993).
Riparian
vegetation
promotes
deposition
of
silt
as
new
soil
during
periods
of
flood,
without
which
key
riparian
species
such
as
alders,
willows,
and
cottonwoods
could
not
reproduce.
Also,
riparian
vegetation
provides
important
substrates
for
aquatic
invertebrates,
cover
for
predator
avoidance,
and
resting
habitat
for
many
fish
species.
The
dead
organic
matter
or
detritus
from
the
riparian
vegetation
is
an
important
source
of
nutrients
to
streams,
estuaries,
and
the
marine
environments.
Riparian
22
vegetation
that
is
carried
from
upland
areas
and
deposited
in
estuaries
is
a
major
source
of
food
and
habitat
for
obigatory,
wood­
boring
marine
invertebrates
which
break
down
and
pass
usable
carbon
into
the
water's
current
where
it
enters
the
detrital­
based
marine
food
web
(
Sedell
and
Maser
1994).
As
much
as
99
percent
of
the
annual
energy
input,
the
food
base
for
all
aquatic
communities,
comes
from
riparian
vegetation
(
Reynolds
et
al.
1993).
Removal
of
streamside
vegetation
simplifies
channel
banks
and
destroys
shelter
for
rearing
steelhead,
simplifies
channel
shape
so
that
are
fewer
pools
and
riffles,
and
eventually
leads
to
a
widening
of
channels
that
are
more
prone
to
warming
by
sunlight
(
Botkin
et
al.
1995;
California
Advisory
Committee
on
Salmon
and
Steelhead
Trout
1988;
California
Department
of
Fish
and
Game
1994).

Reduction
in
tall
tree
shade
canopy
brought
about
by
the
initial
and
continued
logging
of
stands
adjacent
to
and
in
riparian
zones,
has
resulted
in
significant
increases
in
water
temperatures
(
Bisson
et
al.
1987;
California
Department
of
Fish
and
Game
1994;
Forest
Ecosystem
Management
Assessment
Team
1993).
The
shading
effect
of
riparian
vegetation
along
fishbearing
and
smaller
tributary
streams
provides
significant
temperature­
moderating
effects
to
the
adjacent
watercourses.
Such
moderation
in
temperatures
can
determine
the
suitability
of
rivers
and
streams
for
anadromous
salmonids.
The
lack
of,
or
removal
of,
shading
along
streams
can
increase
water
temperature
by
11.7
to
18
E
F
(
7.8
to
11.3
E
C)
(
Reynolds
et
al.
1993).
Shading
can
also
significantly
diminish
daily
temperature
variations
in
streams.
Many
Pacific
North
American
watersheds
supporting
anadromous
salmonids
have
been
logged
more
than
once
resulting
in
cumulative
removal
of
most
of
the
original
dense
conifer
overstory
covering
streams.

High
stream
temperatures
become
a
chronic
problem
for
fish
populations
due
to
a
lack
of
adequate
shading.
Temperature
increases
can
shift
ecological
relationships
allowing
fish
species,

such
as
sunfish,
suckers,
dace,
squawfish,
and
shiners,
to
become
numerically
dominant
over
salmonids
(
Higgins
et
al.
1992;
Reeves,
1985).
Water
temperatures
in
many
streams
throughout
California
and
the
Pacific
Northwest
are
now
approaching
upper
lethal
temperatures
for
anadromous
salmonids.
A
review
of
U.
S.
Geological
Survey
gauging
station
data
for
selected
major
river
basins
throughout
the
west
coast
(
Busby
et
al.
1996)
indicates
that
summer
water
temperatures
have
increased
in
nearly
all
basins.
Kubicek
(
1977)
and
the
U.
S.
Fish
and
Wildlife
23
Service
(
1991)
reported
that
main
river
channels
have
become
increasingly
unsuitable
for
all
salmonids
during
the
summer
months
due
to
high
stream
temperatures.
Removal
of
riparian
vegetation
can
also
make
streams
in
interior
areas
more
subject
to
freezing
and
anchor­
ice
formation
during
winter
months
(
Higgins
et
al.
1992).

Cumulative
effects
of
past
and
present
human
activities
have
degraded
aquatic
and
associated
riparian
systems
substantially.
Activities
such
as
mining,
timber
and
fuelwood
harvesting,

channelization,
dam
and
levee
construction,
bank
protection,
and
stream
flow
regulation
have
altered
the
riparian
system
and
contributed
to
vegetation
loss
(
Reynolds
et
al.
1993).
As
a
result,
few
high­
quality
aquatic
ecosystems
remain
in
the
United
States.
In
1982,
the
U.
S.

National
Park
Service
completed
the
"
Nationwide
Rivers
Inventory"
and
found
that
of
3.25
million
stream
miles
(
5.24
million
km)
examined
in
the
lower
48
states,
less
than
2
percent
were
considered
of
"
high
natural
quality"
(
Behnke
1990).
Edwards
et
al.
(
1992)
reported
that
approximately
55
percent
of
the
27,000
stream
miles
(
43,000
km)
in
Oregon
are
either
severely
or
moderately
impacted
by
nonpoint­
source
pollution.
Historically,
the
Sacramento
River
was
bordered
by
up
to
500,000
acres
of
riparian
forest,
with
bands
of
vegetation
spreading
four
to
five
miles
(
6
to
8
km)
wide.
In
the
last
century
and
one­
half,
agricultural
conversion
and
urbanization
have
been
the
primary
factors
eliminating
riparian
habitat
(
California
State
Lands
Commission
1993;
Forest
Ecosystem
Management
Assessment
Team
1993;
Reiner
and
Griggs
1989).
Conversion
of
riparian
woodlands
by
agriculture
and
urbanization
in
California's
Central
Valley
has
reduced
the
present
habitat
to
less
than
2
percent
of
the
original
acreage
(
Nature
Conservancy
1990).
Martin
(
1986)
reported
a
99.9
percent
loss
of
Central
Valley
riparian
oak
forest.

The
phenomenon
of
diminishing
aquatic
ecosystem
quality
is
not
limited
to
riverine
environments.
Dahl
(
1990)
and
Tiner
(
1991)
reported
that
between
the
1780'
s
and
1980'
s,
the
lower
48
states
lost
approximately
53
percent
of
all
wetlands.
Wetlands
in
Washington
and
Oregon
have
diminished
in
area
by
over
33
percent
(
Dahl
1990)
and
many
of
the
remaining
wetlands
are
degraded.
The
riparian
wetland
habitat
within
California's
Central
Valley
has
been
reduced
by
about
95
percent
and
91
percent
statewide
(
Barbour
et
al.
1991;
Dahl
1990;
Jensen
24
et
al.
1990;
Reynolds
et
al.
1993).
However,
most
of
these
studies
only
examined
wetland
loss
and
did
not
assess
the
health
of
those
remaining,
thus,
the
actual
area
of
high
quality
wetlands
may
likely
be
much
lower
than
the
total
reported
acres.

d.
Loss
of
Habitat
Complexity
and
Connectivity
In
Pacific
Northwest
and
California
streams,
habitat
simplification
has
lead
to
a
decrease
in
the
diversity
of
anadromous
salmonid
species
complex
(
Bisson
and
Sedell
1984;
Hicks
1990;
Li
et
al.
1987;
Reeves
et
al.
1993).
Habitat
simplification
may
result
from
various
land­
use
activities,

including
timber
harvest,
grazing,
urbanization
(
California
State
Lands
Commission
1993;
Forest
Ecosystem
Management
Assessment
Team
1993;
Frissel
1992)
and
agriculture
(
Forest
Ecosystem
Management
Assessment
Team
1993).
Timber
harvest
and
range
management
activities
can
result
in
a
decrease
in
the
number
and
quality
of
pool
habitats
(
Sullivan
et
al.

1987).
Reduction
of
wood
in
the
stream
channel,
either
from
past
or
present
activities,
generally
reduces
pool
quantity
and
quality,
alters
stream
shading
which
can
affect
water
temperature
regimes
and
nutrient
input,
and
can
eliminate
critical
stream
habitat
needed
for
both
vertebrate
and
invertebrate
populations.
Removal
of
vegetation
also
can
destablize
marginally
stable
slopes
by
increasing
the
subsurface
water
load,
lowering
root
strength,
and
altering
water
flow
patterns
in
the
slope
(
Forest
Ecosystem
Management
Assessment
Team
1993).
Skid
trails,
logging
roads,
and
road
crossings
can
be
direct
sources
of
sediment
to
the
stream
and
can
act
as
direct
conduits
for
water
yield
and
sediment
from
other
sources.
Constricting
channels
with
culverts,

bridge
approaches,
and
streamside
roads
can
reduce
stream
meandering,
partially
constrict
or
channelize
flows,
reduce
pool
maintenance,
and
can
preclude
passage
of
anadromous
salmonids
(
Forest
Ecosystem
Management
Assessment
Team
1993).

Diverse
habitats
support
diverse
species
assemblages
and
communities.
This
diversity
contributes
to
sustained
production
and
provides
stability
for
the
entire
ecosystem.
Further,

habitat
diversity
can
also
mediate
biotic
interactions
such
as
competition
(
Hartman
1965)
and
predation
(
Schlosser
1988).
Attributes
of
habitat
diversity
include
a
variety
and
range
of
hydraulic
parameters
(
Kaufman
1987),
abundance
and
size
of
wood
(
Bisson
1987),
and
variety
of
bed
substrate
(
Sullivan
et
al.
1987).
25
A
primary
characteristic
of
high
quality
aquatic
ecosystems
is
an
abundance
of
large
pool
habitats.
In
many
tributaries
within
the
range
of
steelhead,
the
number
of
large,
deep
pools
have
decreased.
In
National
Forests
within
the
range
of
the
northern
spotted
owl
in
western
and
eastern
Washington,
there
has
been
a
58
percent
reduction
in
the
number
of
large,
deep
pools
(
Forest
Ecosystem
Management
Assessment
Team
1993).
A
similar
trend
has
been
observed
in
streams
on
private
lands
in
coastal
Oregon,
where
large,
deep
pools
have
decreased
by
as
much
as
80
percent
(
Forest
Ecosystem
Management
Assessment
Team
1993).
Primary
reasons
for
the
loss
of
pools
are:
filling
by
sediments
(
Megahan
1982),
loss
of
pool­
forming
structures
such
as
boulders
and
large
wood
(
Sullivan
et
al.
1987),
and
loss
of
sinuosity
by
channelization
(
Benner
1992;
Furniss
et
al.
1991).

An
important
consideration
for
maintaining
aquatic
and
riparian
ecosystem
functions
is
the
degree
of
spatial
and
temporal
connectivity
within
and
between
watersheds
(
Naiman
et
al.

1992).
Lateral,
vertical,
and
drainage
network
linkages
are
critical
to
aquatic
system
function.

Important
connections
within
basins
include
linkages
among
headwater
tributaries
and
downstream
channels
as
paths
for
water,
sediment
and
disturbances
(
Forest
Ecosystem
Management
Assessment
Team
1993).
Further,
linkages
among
floodplains,
surface
water,
and
ground
water
systems
as
exchange
for
water,
sediment
and
nutrients
are
also
important
(
Forest
Ecosystem
Management
Assessment
Team
1993).
Unobstructed
physical
and
chemical
paths
to
areas
critical
for
fulfilling
life­
history
requirements
of
aquatic
and
riparian
dependent
species
must
also
be
maintained
to
ensure
ecosystem
stability.
Logging,
agricultural,
and
urbanization
activities
have
reduced
the
connectivity
of
aquatic
and
riparian
habitats,
thereby
decreasing
and
limiting
the
relative
diversity
of
numerous
salmonid­
producing
watersheds.

2.
Mining
The
impacts
of
historical
mining
operations
are
evident
in
many
streams
of
the
Pacific
Northwest
and
California.
Past
mining
activities
routinely
resulted
in
the
removal
of
spawning
gravels
from
streams,
channelization
of
streams
from
dredging
activities,
and
leaching
of
toxic
effluents
into
streams
(
Bottom
et
al.
1985;
California
State
Lands
Commission
1993).
Many
of
the
effects
of
past
mining
operations
still
impact
steelhead
habitat
today.
Current
mining
practices
include
26
suction
dredging,
placer
mining,
lode
mining
and
gravel
mining.
Present
day
mining
practices
are
typically
less
intrusive
than
historic
operations
(
hydraulic
mining);
however,
adverse
impacts
to
salmonid
habitat
still
occur
as
a
result
of
present­
day
mining
activities.

Sand
and
gravel
are
used
for
a
large
variety
of
construction
activities
including
base
material
and
asphalt,
road
bedding,
drain
rock
for
leach
fields,
and
aggregate
mix
for
buildings
and
highways.

Since
the
end
of
World
War
II,
rapid
human
population
growth
and
the
consequent
construction
boom
has
maintained
high
demand
for
aggregate
material.
In
1986,
the
production
of
sand
and
gravel
in
California
alone,
primarily
derived
from
river
channels
and
their
flood
plains,
was
estimated
at
128.5
million
tons
(
116
million
kilograms
(
kg))
with
an
estimated
value
of
nearly
$
500
million
(
Sandecki
1989);
nearly
double
the
estimated
production
of
65
million
tons
(
59
million
kg)
in
1955
(
California
State
Lands
Commission
1993).

Most
aggregate
is
derived
principally
from
pits
in
active
flood
plains,
pits
in
inactive
river
terrace
deposits,
or
directly
from
the
active
channel.
Other
sources
include
hard
rock
quarries
and
mining
from
deposits
within
reservoirs.
Extraction
sites
located
along
or
in
active
flood
plains
present
particular
problems
for
anadromous
salmonids.
Physical
alteration
of
the
stream
channel
may
result
in
the
destruction
of
existing
riparian
vegetation
and
the
reduction
of
available
area
for
seedling
establishment
(
California
State
Lands
Commission
1993).
As
discussed
previously,

loss
of
vegetation
impacts
riparian
and
aquatic
habitat
by
causing
a
loss
of
the
temperaturemoderating
effects
of
shade
and
cover,
and
habitat
diversity.
Extensive
degradation
may
induce
a
decline
in
the
alluvial
water
table,
as
the
banks
are
effectively
drained
to
a
lowered
level,

affecting
riparian
vegetation
and
water
supply
(
Woodward­
Clyde
Consultants
1976).
Altering
the
natural
channel
configuration
will
reduce
salmonid
habitat
diversity
by
creating
a
wide,

shallow
channel
lacking
in
the
pools
and
cover
necessary
for
all
life
stages
of
anadromous
salmonids.

There
are
no
accurate
records
of
the
number
of
inactive
mines
on
the
West
Coast;
however,

many
abandoned
mines
contribute
toxic
substances
into
rivers
and
streams.
In
many
cases,
past
hydraulic
and
explosive
mining
have
exposed
rock
and
metal
ores
to
weathering
conditions
27
which
has
resulted
in
the
formation
of
acidic
compounds
(
California
State
Lands
Commission
1993).
Further,
waste
products
resulting
from
past
and
present
mining
activities,
include
cyanide
(
an
agent
used
to
extract
gold
from
ore),
copper,
zinc,
cadmium,
mercury,
asbestos,

nickel,
chromium,
and
lead.
These
products
are
extremely
hazardous
to
both
humans
and
aquatic
life.
An
example
of
an
inactive
mine
that
is
causing
severe
impacts
to
water
quality
is
the
Iron
Mountain
Mine
in
the
Sacramento
River
watershed,
California
(
California
Department
of
Fish
and
Game
1995).
Toxic
substances
are
released
directly
into
the
Sacramento
River,
and
water
stored
in
an
upstream
reservoir
(
Shasta
Reservoir)
must
be
released
to
dilute
toxic
spills
from
the
mine
(
California
Department
of
Fish
and
Game
1995).
These
water
releases
could
provide
alternative
benefits,
such
as
for
migration
flows,
temperature
reduction,
or
high
delta
outflows
if
the
releases
were
not
required
for
mitigating
mining
impacts
(
California
Department
of
Fish
and
Game
1995).

3.
Urbanization
Urbanization
has
led
to
degraded
steelhead
habitat
through
stream
channelization,
floodplain
drainage,
and
riparian
damage
(
Botkin
et
al.
1995).
The
distribution
of
large
floods
over
time
reflects
the
precipitation
and
runoff
region
of
the
watershed,
and
large
floods
are
natural
and
necessary
for
the
drainage
of
the
watershed
and
maintenance
of
the
river
channel.
When
watersheds
are
urbanized,
problems
may
result
simply
because
structures
are
placed
in
the
path
of
natural
processes,
or
because
the
urbanization
itself
has
induced
changes
in
the
hydrologic
regime,
which
in
turn
impact
structures.
Point
source
(
PS)
and
nonpoint
source
pollution
(
NPS)

occurs
at
almost
every
point
that
urbanization
activity
influences
the
watershed.
Impervious
surfaces
(
i.
e.
concrete)
reduce
water
infiltration
and
increase
runoff,
thus
creating
greater
flood
hazard
(
Leopold
1968).
Flood
control
and
land
drainage
schemes
may
increase
the
flood
risk
downstream
by
concentrating
runoff.
A
flashy
discharge
pattern
results
in
increased
bank
erosion
with
subsequent
loss
of
riparian
vegetation,
undercut
banks
and
stream
channel
widening.
Sediments
washed
from
the
urban
areas
and
deposited
in
river
waters
include
trace
metals
such
as
copper,
cadmium,
zinc,
and
lead
(
California
State
Lands
Commission
1993).

These,
together
with
pesticides,
herbicides,
fertilizers,
gasoline,
and
other
petroleum
products,

contaminate
drainage
waters
and
destroy
aquatic
life
necessary
for
steelhead
survival.
The
9United
States
v.
Washington,
443
U.
S.
658
(
1979).

10United
States
v.
Oregon,
657
F.
2d
1009
(
9th
Cir.
1981).

28
California
State
Water
Resources
Control
Board
(
1991)
reported
that
NPS
pollution
is
the
cause
of
50
to
80
percent
of
impairment
to
water
bodies
in
California.

In
most
western
states,
about
80
to
90
percent
of
the
riparian
habitat
has
been
eliminated.
While
historical
uses
of
riparian
areas
(
e.
g.,
fuelwood
cutting,
clearing
for
agricultural
uses)
have
substantially
decreased,
urbanization
still
poses
a
serious
threat
to
remaining
riparian
areas.

Riversides
are
desirable
places
to
locate
homes,
businesses,
and
industry.
Further,
development
within
the
flood
plain
results
in
vegetation
removal,
stream
channelization,
habitat
instability,
and
point
and
nonpoint
source
pollution.

II.
Over­
utilization.

A.
Commercial,
Recreational,
and
Tribal
Harvest.

Historically,
steelhead
were
abundant
in
many
western
coastal
and
interior
streams
of
the
United
States
and
have
supported
substantial
tribal
and
sport
fisheries,
contributing
millions
of
dollars
to
numerous
local
economies
(
Nickelson
et
al.
1992).
Over­
fishing
in
the
early
days
of
the
European
settlement
led
to
the
depletion
of
many
stocks
of
salmon
and
steelhead
even
before
extensive
habitat
degradation.
However,
following
the
degradation
of
many
west
coast
aquatic
and
riparian
ecosystems,
exploitation
rates
may
have
been
higher
than
populations
could
sustain.

Therefore,
harvest
may
have
contributed
to
the
further
decline
of
some
populations.

Steelhead
are
harvested
by
both
non­
Indian
and
Indian
fishermen
in
Washington
and
Oregon.

Prior
to
1974,
steelhead
were
primarily
harvested
in
recreational
fisheries.
After
the
mid­
1970'
s,

two
federal
court
rulings
governed
the
allocation
between
these
two
groups.
United
States
v.

Washington9
set
the
harvest
allocation
criteria
for
the
Puget
Sound
and
the
Washington
coast
north
of
Willapa
Bay.
United
States
v.
Oregon10
set
the
management
criteria
for
runs
returning
upstream
of
Bonneville
Dam
in
the
Columbia
River
system.
Only
runs
returning
to
Columbia
River
tributaries
downstream
of
Bonneville
Dam,
streams
entering
Willapa
Bay,
and
certain
29
Indian
reservations
are
not
covered
by
these
decisions
or
are
not
subject
to
sharing
between
the
parties
(
WDFW
1995).

The
Northwest
Power
Planning
Council
(
1986)
estimated
that
the
aboriginal
catch
ranged
from
about
4.5
to
5.6
million
salmon
and
steelhead
annually
in
the
Columbia
River
Basin.
The
harvest
of
steelhead
in
the
Columbia
River
peaked
in
1892
at
over
4.9
million
pounds
(
19
million
kg)

(
WDF
and
ODFW
1994).
Commercial
harvest
of
steelhead
has
been
limited
to
Native
Americans
in
the
Columbia
River
since
1975,
and
in
the
Pacific
Southwest
since
1924
(
Barnhart
1986,
WDF
and
ODFW
1994).
Tribal
harvest
of
steelhead
at
Celilo
Falls
on
the
Columbia
River
ranged
from
25,000
to
60,000
fish
annually
from
1938
to
1974
(
WDF
and
ODFW
1994).

During
the
1980'
s,
Native
American
commercial
catches
in
the
Columbia
River
ranged
from
10,000
to
70,000
while
ceremonial
and
subsistence
fisheries
have
ranged
from
less
than
1,000
to
about
10,000.
As
recent
as
1993,
the
Native
American
tribal
fishery
harvested
a
total
of
about
27,500
steelhead
during
the
winter
and
fall
treaty
commercial
fishing
seasons
in
the
Columbia
River
(
WDF
and
ODFW
1994).
This
was
a
decrease
from
a
harvest
of
about
50,000
in
1992.

In
California,
steelhead
are
taken
during
the
Yurok
tribe's
fall
chinook
salmon
subsistence
fishery
in
the
Klamath
River.
From
1984
through
1992,
an
estimated
2,350
steelhead
were
captured,

with
a
range
of
472
in
1984
to
68
in
1992,
and
an
estimated
mean
of
260
steelhead
per
year
(
Craig
and
Fletcher
1994).
No
data
was
available
from
the
Hoopa
or
Klamath
tribes
net
fisheries
in
the
Klamath
Basin.

Steelhead
have
remained
important
fisheries
for
recreational
purposes.
In
the
Columbia
River
recreational
fishery,
the
majority
of
sport
catch
occurs
in
the
tributaries
located
in
Oregon
and
Washington.
Most
tributaries
are
limited
to
hatchery­
marked
steelhead
harvest
only.
Sport
catch
of
upriver
steelhead
in
Oregon,
Washington
and
Idaho
has
increased
from
21,700
in
1979
to
an
average
of
about
90,000
since
1985,
while
sport
catch
of
winter
steelhead
in
Oregon
and
Washington
has
ranged
from
about
70,000
in
1980
to
about
25,000
in
1994
(
WDF
and
ODFW
1994).
The
combined
Oregon,
Washington,
and
Idaho
sport
catch
of
steelhead
in
the
Columbia
River
and
tributaries
from
the
1992­
93
run
was
about
150,000,
the
highest
on
record
(
WDF
and
30
ODFW
1994).

Estimates
of
steelhead
catch
in
California's
rivers
by
sport
fishers
are
estimates
based
on
limited
monitoring.
In
the
early
1960'
s,
there
was
an
estimated
harvest
of
122,000
adult
steelhead
per
year
and
an
unknown
quantity
of
harvested
juvenile
steelhead
(
California
Department
of
Fish
and
Game
1965).
Harvest
rate
estimates
for
the
Klamath
River
for
the
1977­
78
through
the
1982­
83
seasons
ranged
from
7.4%
to
19.2%
and
averaged
12.1%.
Harvest
rates
for
wild
steelhead
are
similar:
wild
steelhead
in
the
Trinity
River
were
harvested
at
rates
of
28.0%,

12.5%
and
17.3%
in
1978­
79,
1980­
81,
and
1982­
83
seasons,
respectively
(
DFG,
unpublished
data),
and
sport
harvest
of
wild
steelhead
in
the
South
Fork
Trinity
River
was
estimated
to
be
5.9%,
18.0%,
8.0%,
and
20.2%
during
the
1988­
89,
1989­
90,
1990­
91,
and
1991­
92
seasons,

respectively
(
Mills
and
Wilson
1991,
Wilson
and
Mills
1992,
Wilson
and
Collins
1992,
Collins
and
Wilson
1994).
The
average
estimated
harvest
rate
on
adult
steelhead
above
Red
Bluff
Diversion
Dam
on
the
Upper
Sacramento
River
for
the
three
year
period
1991­
92
through
1993­

94
was
16.0%
(
DFG,
unpublished
data).

In
1991,
there
were
an
estimated
99,700
steelhead
anglers
in
California
(
California
Department
of
Fish
and
Game
1991).
The
California
Department
of
Fish
and
Game
(
CDFG)
has
just
recently
(
as
of
1993)
developed
and
required
a
"
steelhead
catch
report
card."
Approximately
77,500
report
cards
were
purchased
by
steelhead
anglers
in
1993,
and
sales
of
the
1994
report
card
were
about
the
same.
Preliminary
results
for
1993
show
that
an
estimated
40,500
steelhead
were
harvested
state­
wide
in
California,
with
71
percent
of
the
effort
occurring
along
the
northern
California
coast,
primarily
in
the
Smith,
Klamath,
Trinity,
and
Mad
Rivers
(
T.
Jackson
pers.
comm.).
Sport
fishing
catch
rates
are
low
everywhere
in
the
state
indicating
declining
steelhead
population
numbers,
irrespective
of
reliable
steelhead
population
estimates
(
McEwan
and
Jackson
1996).

Illegal
harvest
can
be
a
serious
problem
for
salmonids
on
their
spawning
beds
and
on
their
summer
rearing/
holding
habitats.
Roelofs
(
1983)
cited
poaching
as
a
serious
problem
on
summer
steelhead
in
northern
California
streams.
Large
portions
of
spring
run
chinook
salmon
31
and
summer
steelhead
runs
often
congregate
in
just
a
few
cool
pools,
increasing
their
vulnerability
to
poaching.
Rivers
considered
to
have
a
serious
poaching
problem
include
most
tributaries
of
the
North
Umpqua,
Klamath
and
Trinity,
and
the
Middle
Fork
Eel
Rivers,

Redwood
Creek,
several
tributaries
of
the
Sacramento
River,
and
several
coastal
rivers
south
of
San
Francisco
Bay.

B.
Scientific
Utilization.

Fishery
agencies
and
Native
American
tribes,
in
cooperation
with
the
U.
S.
Army
Corps
of
Engineers
(
COE),
the
Bonneville
Power
Administration
(
BPA),
and
others,
annually
conduct
a
coordinated
program
to
monitor
the
downstream
migration
of
natural
and
hatchery
produced
juvenile
salmonids
in
the
Columbia
River
Basin
and
in
coastal
Washington
and
Oregon.
Direct
sampling
is
conducted
on
a
daily
basis
at
the
upper
Snake
River
and
Clearwater
River
traps,

Lower
Granite
Dam,
Little
Goose
Dam,
and
Lower
Monumental
Dam
on
the
Snake
River,
and
McNary
Dam,
John
Day
Dam,
The
Dalles
Dam,
and
Bonneville
Dam
on
the
Columbia
River.

Data
collected
during
this
sampling
are
used
to
monitor
bypass
performance
and
to
manage
the
water
budget,
spill,
and
fish
transportation
programs.
Until
recently,
sampling
of
juvenile
salmonids
at
Lower
Granite,
Little
Goose,
and
McNary
Dams
has
been
limited
to
8
percent
of
the
total
outmigration,
providing
an
additional
2
percent
of
the
outmigration
for
remaining
sampling
sites
(
Columbia
Basin
Fish
and
Wildlife
Authority
1991b).
At
the
present,
outmigrant
sampling
has
been
decreased
and
limited
to
3
percent
of
the
total
outmigration
at
all
sites
(
CBIT
and
SFFWA
1993).
While
this
sampling
may
result
in
the
delay
and
handling
of
juveniles,
it
does
not
necessarily
result
in
the
mortality
of
those
individuals
sampled
(
USFWS
1995).

In
California,
most
of
the
scientific
collection
permits
are
issued
to
environmental
consultants,

federal
resource
agencies,
and
universities
by
the
CDFG.
The
Department
controls
scientific
utilization
of
steelhead
through
the
issuance
of
Scientific
Collector's
Permits.
Take
of
steelhead
in
excess
of
sportfishing
limits
is
prohibited
unless
specifically
authorized
in
the
permit.

Regulation
of
take
is
controlled
by
conditioning
individual
permits.
The
CDFG
does
require
reporting
of
any
steelhead
trout
taken
incidental
to
other
monitoring
activities;
however,
no
comprehensive
total
or
estimate
of
steelhead
mortalities
related
to
scientific
sampling
are
kept
32
for
any
watershed
or
steelhead
stock
in
the
state
(
D.
McEwan
pers.
comm.).
The
CDFG
does
not
believe
that
indirect
mortalities
associated
with
scientific
utilization
have
had,
or
are
having,

a
detrimental
effect
on
any
steelhead
population
in
California
(
D.
McEwan
pers.
comm.).

C.
Ocean
Harvest
Steelhead
are
not
generally
caught
by
commercial
or
recreational
fishers
in
the
ocean.
However,

although
little
documented
evidence
exists,
high
seas
driftnet
fishing
has
been
implicated
as
a
cause
for
decline
of
steelhead
from
coastal
streams
along
the
North
American
Pacific
Coast
(
Light
et
al.
1988).
Observations
of
returning
steelhead
to
Rowdy
Creek
Fish
Hatchery
on
the
Smith
River
in
1992
showed
healed
gillnet
scars
on
30
of
155
adults
(
Higgins
et
al.
1992),
and
many
of
the
observed
returning
adults
to
several
Santa
Cruz
County
streams
have
also
shown
a
high
incidence
of
gillnet
scars
(
D.
Streig
pers.
comm.
1995).

Based
on
recoveries
of
marked
and
tagged
North
American
steelhead,
high
seas
steelhead
distribution
and
driftnet
fisheries
overlap
(
Light
et
al.
1988,
Burgner
et
al.
1992).
The
recent
decline
in
steelhead
abundance
may
be
partially
attributed
to
the
harvest
of
steelhead
in
high
seas
driftnet
fisheries
(
Anonymous
1989
cited
in
Cooper
and
Johnson
1992).
Cooper
and
Johnson
(
1992)
reported
that
the
authorized
Japanese
mothership
salmon
driftnet
fishery
was
largest
between
1973­
1977
when
a
total
of
21.4
million
salmon
were
harvested
per
year.
The
authorized
Japanese
land­
based
salmon
fishery
harvested
30.2
million
fish
per
year,
which
included
a
steelhead
catch
ranging
from
2,761
in
1990
to
28,900
in
1983
(
Cooper
and
Johnson
1992).
However,
Cooper
and
Johnson
(
1992)
estimated
that
less
than
1
percent
of
the
total
salmonid
catch
in
both
fisheries
were
steelhead.

In
the
past,
an
authorized
high
seas
squid
fishery
was
operated
by
Japan,
the
Republic
of
Korea,

and
Taiwan.
Benton
(
1990,
as
cited
in
Cooper
and
Johnson
1992)
estimated
that
by
1988,

approximately
two
million
miles
(
3.2
million
km)
of
squid
driftnet
were
set
per
year.
Pella
et
al.

(
1991)
estimated
the
salmonid
bycatch
and
the
number
of
salmonid
dropouts
during
net
retrieval
in
the
1990
authorized
squid
fishery.
They
reported
that
the
Japanese
bycatch
was
210,000
fish
caught
and
21,000
dropout
fish,
with
the
estimated
mean
steelhead
harvest
portion
of
9,200
fish
33
or
roughly
4
percent
of
the
total
bycatch.
The
Korean
and
Taiwanese
steelhead
bycatch
was
estimated
at
35
and
two
steelhead
harvested,
respectively.
The
combined
authorized
high
seas
driftnet
fisheries
caught
less
than
3
percent
of
the
estimated
1.6
million
steelhead
adults
that
return
to
the
Pacific
coast
of
North
America
from
1983
through
1990
(
Light
1987,
Cooper
and
Johnson
1992,
Burgner
et
al.
1992).
Japan,
with
largest
North
Pacific
driftnet
fleet,
ceased
such
activities
in
May
of
1992.
Furthermore,
the
United
Nations
continues
efforts
to
halt
drift
gillnet
fishing
by
South
Korea
and
Taiwan.

Unauthorized
fishing
on
the
high
seas
may
result
in
a
substantial
level
of
salmonid
mortality
(
Pella
et
al.
1991,
Cooper
and
Johnson
1992).
Cooper
and
Johnson
(
1992)
reported
that
a
total
of
71
and
165
foreign
vessels
were
observed
outside
authorized
fishing
areas
in
1990
and
1991,

respectively.
It
was
estimated
that
the
unauthorized
high
seas
driftnet
fisheries
harvest
between
2
percent
(
32,000)
and
28
percent
(
448,000)
of
the
steelhead
that
are
destined
to
return
to
the
Pacific
coast
of
North
America
(
Cooper
and
Johnson
1992).
However,
even
if
the
high
seas
driftnet
fisheries
harvested
a
combined
31
percent
(
3
percent
authorized
and
28
percent
unauthorized)
of
the
steelhead,
the
greater
than
50
percent
decline
in
North
American
steelhead
runs
observed
between
1986
through
1991
cannot
be
solely
attributed
to
this
fishery
(
Cooper
and
Johnson
1992).

III.
Disease
or
Predation.

A.
Disease.

Infectious
disease
is
one
of
many
factors
which
can
influence
adult
and
juvenile
survival.

Steelhead
are
exposed
to
numerous
bacterial,
protozoan,
viral,
and
parasitic
organisms
in
spawning
and
rearing
areas,
hatcheries,
migratory
routes,
and
the
marine
environments.
Specific
diseases
such
as
bacterial
kidney
disease
(
BKD),
ceratomyxosis,
columnaris,
Furunculosis,

infectious
hematopoietic
necrosis
(
IHNV),
redmouth
and
black
spot
disease,
Erythrocytic
Inclusion
Body
Syndrome
(
EIBS),
and
whirling
disease
among
others
are
present
and
are
known
to
affect
steelhead
and
salmon
(
Rucker
et
al.
1953,
Wood
1979,
Leek
1987,
Foott
et
al.
1994,

Gould
and
Wedemeyer
undated).
Very
little
current
or
historical
information
exists
to
quantify
changes
in
infection
levels
and
mortality
rates
attributable
to
these
diseases
for
steelhead.
34
However,
studies
have
shown
that
native
fish
tend
to
be
less
susceptible
to
pathogens
then
hatchery­
reared
fish
(
Buchanon
et
al.
1983,
Sanders
et
al.
1992).

Wild
steelhead
may
contract
diseases
which
are
spread
through
the
water
column
(
i.
e.,

waterborne
pathogens)
(
Buchanan
et
al.
1983).
Disease
may
also
be
contracted
through
interbreeding
with
infected
hatchery
fish
(
Fryer
and
Sanders
1981,
Evelyn
et
al.
1984
and
1986).

A
fish
may
be
infected
yet
not
be
in
a
clinical
disease
state
with
reduced
performance.

Salmonids
typically
are
infected
with
several
pathogens
during
their
life
cycle.
However,
high
infection
(
number
of
organisms
per
host)
and
stressful
conditions
(
crowding
in
hatchery
raceways,
release
from
a
hatchery
into
a
riverine
environment,
high
and
low
water
temperatures,

etc.)
usually
characterize
the
system
before
a
disease
state
occurs
in
the
fish.

Recently,
USFWS
and
CDFG
monitored
the
health
and
physiology
of
natural
and
hatchery
chinook
salmon
and
steelhead
trout
in
the
Klamath
and
Trinity
River
basins
(
Foott
et
al.
1994).

The
bacterium,
Renibacterium
salmoninarum,
causative
agent
of
BKD,
and
the
trematode
parasite,
Nanophyetus
salmincola,
were
identified
as
the
most
significant
pathogens
affecting
both
natural
and
hatchery
smolt
health
in
the
basin.
Natural
steelhead
smolts
in
the
Trinity
River
were
found
to
have
a
incidence
of
R.
salmoninarum,
much
higher
than
in
the
Trinity
River
hatchery
stock.
In
1991,
over
twice
the
percentage
of
natural
steelhead
(
21
percent)
as
hatchery
fish
(
10
percent)
were
found
to
be
infected
with
R.
salmoninarum
(
Foott
et
al.
1994).
Sampling
conducted
in
1992
showed
that
53
percent
of
the
natural
steelhead
tested
positive
for
the
bacterium.
This
is
among
the
highest
positive
percentage
ever
recorded;
however,
no
signs
of
clinical
BKD
were
observed
in
either
hatchery
or
natural
steelhead.

It
is
possible
that
steelhead
can
tolerate
R.
salmoninarum
infection
better
than
chinook
or
coho
salmon
(
Foott
et
al.
1994).
Many
of
the
natural
and
hatchery
steelhead
populations
throughout
California's
coast
and
central
valley
have
tested
positive
for
R.
salmoninarum
(
Foott
1992).
The
impacts
of
BKD
disease
are
subtle.
Juvenile
salmonids
may
survive
well
in
their
journey
downstream,
but
may
be
unable
to
make
appropriate
changes
in
kidney
function
for
a
successful
transition
to
sea
water
(
Foott
1992).
35
Stress
during
migration
may
also
cause
this
disease
to
come
out
of
remission
(
Schreck
1987).

Passage
through
dams,
bypasses,
and
spillways
increase
physiological
stress
and
physical
injury
in
migrating
juvenile
salmonids
(
Matthews
et
al.
1986,
Maule
et
al.
1988);
in
turn,
this
may
increase
the
susceptibility
of
migrating
salmonids
to
pathogens
(
Maule
et
al.
1988).
Adult
steelhead
are
also
subject
to
increased
stress
from
fallback
at
dams,
crowding
in
ladders,
and
skin
abrasion.
Another
critical
factor
in
controlling
disease
epidemics
is
the
presence
of
adequate
water
quantity
and
quality
during
late
summer.
As
water
quantity
and
quality
diminishes,
and
freshwater
habitat
becomes
more
degraded,
many
previously
infected
salmonid
populations
may
experience
large
mortalities
since
added
stress
can
trigger
the
onset
disease.

These
factors,
in
combination
with
high
water
temperatures
common
in
various
rivers
and
streams,
may
increase
anadromous
salmonid
susceptibility
and
exposure
to
diseases
(
Holt
et
al.

1975,
Wood
1979).

Until
the
late
1970'
s,
Ceratomyxa
shasta
was
thought
to
be
confined
to
waters
below
the
Deschutes
River
(
Wood
1979).
Recent
investigations
on
adult
summer
chinook
salmon
indicate
that
upper
Snake
River
waters
are
also
infected
(
Chapman
1986).
Operational
problems
associated
with
C.
shasta
began
to
occur
shortly
after
the
opening
of
Iron
Gate
Hatchery,

located
on
the
Klamath
River
in
California
(
CH2M
Hill
1985).
Periodic
outbreaks
of
this
parasite
continued
into
the
early
1980'
s
(
CH2M
Hill
1985).
C.
shasta
is
often
found
in
reservoir
environments
(
Wood
1979);
therefore,
impounding
of
the
upper
Columbia,
Snake,
and
Klamath
Rivers
may
have
contributed
to
the
spread
of
the
parasite.

In
many
cases,
disease
outbreaks
have
occurred
as
a
result
of
introduced,
non­
native
steelhead
populations
susceptible
to
disease
(
KRBFTF
1991).
High
straying
rates
of
non­
native
fish
exacerbate
the
situation
by
spreading
pathogens
throughout
the
native
community
(
KRBFTF
1991).
In
the
early
1970'
s,
many
Trinity
River
Hatchery
steelhead
strayed
to
the
Iron
Gate
Hatchery.
Excess
steelhead
adults
in
the
Iron
Gate
Hatchery
were
then
transferred
to
Shasta,

Scott,
and
other
small
Klamath
River
tributaries
(
KRBFTF
1991).
Carlton
(
1989)
found
that
chinook
salmon
at
Iron
Gate
Hatchery
had
a
4
percent
susceptibility
to
C.
shasta
while
the
Trinity
River
Hatchery
chinook
salmon
had
roughly
a
12
percent
susceptibility.
Hubbell
(
1979)
36
found
similar
resistance
of
Iron
Gate
Hatchery
steelhead
and
Trinity
River
Hatchery
steelhead
(
12
percent).
Hendrickson
et
al.
(
1989)
reported
that
C.
shasta
was
endemic
to
the
Klamath
River,
however,
Foott
et
al.
(
1994)
rarely
found
either
spores
or
other
life
stages
of
C.
shasta
in
fish
collected
in
the
Klamath
River.

B.
Freshwater
Predation.

Predation
on
juvenile
salmon
has
increased
as
a
result
of
water
development
activities
which
have
created
ideal
habitats
for
predators
and
non­
native
species.
Turbulent
conditions
near
dam
bypasses,
turbine
outfalls,
water
conveyances,
and
spillways
disorient
juvenile
steelhead
migrants
and
increase
their
avoidance
response
time,
thus
improving
predator
success
(
Sigismondi
and
Weaver
1988).
Increased
exposure
to
predators
has
also
resulted
from
reduced
water
flow
through
reservoirs;
a
condition
which
has
increased
juvenile
travel
time
(
Columbia
Basin
Fish
and
Wildlife
Authority
1991a).
For
example,
Northern
squawfish
(
Ptychocheilus
oregonensis)

and
avian
predator
populations
have
increased
with
the
formation
of
ideal
predator
foraging
areas
created
by
dam
impoundments.
Results
from
numerous
studies
indicate
that
in
many
reservoirs,
northern
squawfish
are
the
primary
predator
of
juvenile
salmon.

Predators
such
as
walleye
(
Stizostedion
vitreum),
smallmouth
bass
(
Micropterus
dolomieui),

channel
catfish
(
Ictalurus
punctatus),
and
northern
squawfish
(
Ptychocheilus
oregonensis)
have
been
found
to
consume
significant
numbers
of
juvenile
salmon.
In
the
Columbia
and
Snake
Rivers,
these
predators
have
been
found
to
consume
between
9
and
19
percent
of
the
juvenile
salmonids
entering
reservoirs,
with
northern
squawfish
accounting
for
approximately
78
percent
of
this
loss
(
Rieman
et
al.
1991).
Squawfish
consumption
rate
tends
to
be
highest
during
the
summer
months,
which
coincide
with
the
juvenile
steelhead
migration
(
Poe
et
al.
1988).
Several
studies
have
documented
squawfish
population
increases
in
the
Columbia
and
Snake
River
steelhead
migration
corridor.
The
estimated
squawfish
population
in
the
upper
half
of
Lower
Monumental
reservoir
increased
from
120,000
in
1975
to
133,000
in
1976
(
Sims
et
al.
1978),

and
from
68,947
in
1984
to
102,888
in
1986
in
the
John
Day
pool
(
Beamsderfer
and
Rieman
1988).
Lynch
(
1993)
estimated
squawfish
abundance
near
The
Dalles
Dam
tailrace
and
cul­

desac
area
to
range
from
160,000
to
1.7
million
in
1991
and
from
150,000
to
500,000
in
1992.
37
The
Bonneville
Dam
forebay
squawfish
population
was
estimated
in
1980
at
between
6,701
and
23,700
individuals
(
Uremovich
et
al.
1980)
and
again
in
1989
at
between
43,302
and
108,960
(
NMFS
unpublished).

Sacramento
squawfish
(
Ptychocheilus
grandis)
is
a
species
native
to
the
Sacramento
River
Basin
and
has
evolved
with
the
anadromous
salmonids
in
this
system.
However,
rearing
conditions
in
the
Sacramento
River
today
(
e.
g.,
warm
water,
low­
irregular
flow,
standing
water,

diversions)
compared
to
its
natural
state
and
function
70
years
ago,
are
more
conducive
to
warmwater
species
such
as
Sacramento
squawfish
and
striped
bass
than
native
salmonids.
In
the
early
1980'
s,
an
illegal
introduction
of
Sacramento
squawfish
occurred
in
the
Eel
River
Basin
via
Pillsbury
Lake.
Today,
in
little
over
a
decade,
Sacramento
squawfish
have
spread
to
most
areas
of
the
Eel
River
Basin
illustrating
the
fact
that
this
species
is
better
adapted
than
native
salmonids
to
the
artificially
warm
water
conditions.
As
a
result,
Sacramento
squawfish
have
been
found
to
constitute
a
serious
problem
for
native
salmonid
populations
(
Higgins
et
al.
1992,

California
Department
of
Fish
and
Game
1994).
If
increased
water
temperature
and
altered
ecosystem
trends
continue,
a
shift
towards
the
dominance
of
warmwater
species
can
logically
be
expected
(
Reeves
1985).

In
addition
to
the
predators
mentioned
above,
striped
bass
(
Marone
saxatilis)
are
often
thought
to
be
a
significant
predator
of
juvenile
salmonids.
Around
the
turn
of
the
Century,
striped
bass
were
introduced
into
the
Sacramento
River
as
a
forage
and
recreational
fishery.
Attempts
to
plant
striped
bass
in
several
California
coastal
tributaries
have
been
unsuccessful.
Presently,

striped
bass
abundance
is
quite
low
relative
to
the
earlier
part
of
this
century;
however,
striped
bass
are
distributed
throughout
the
California
Aquaduct
system
and
associated
reservoirs
and
have
been
noted
in
Lake
Mendocino
and
the
Russian
River
system.
There
are
no
reliable
data
available
regarding
predation
rates
of
striped
bass
on
any
steelhead
trout
population
in
California
(
D.
McEwan
pers.
comm.).

In
addition
to
predation
by
freshwater
fish
species,
avian
predators
have
also
been
shown
to
impact
juvenile
salmonids.
Such
predation
may
occur
in
freshwater
areas
as
well
in
nearshore
38
marine
environments.
Ruggerone
(
1986)
estimated
that
ring­
billed
gulls
(
Larus
delawarensis)

consumed
2
percent
of
the
salmon
and
steelhead
trout
passing
Wanapum
Dam
during
the
spring
smolt
outmigration
in
1982.
Wood
(
1987)
estimated
that
the
common
merganser
(
Mergus
merganser),
a
known
freshwater
predator
of
juvenile
salmonids,
were
able
to
consume
24
to
65
percent
of
coho
salmon
production
in
coastal
British
Columbia
streams.
Known
avian
predators
in
the
nearshore
marine
environment
include
herons
and
diving
birds
such
as
cormorants
and
alcids
which
include
auklets,
murres,
murrelets,
guillemots,
and
puffins
(
Allen
1974).
Manuwal
(
1977)
estimated
that
in
Washington,
about
5
percent
of
auklet
prey
biomass
was
juvenile
salmon.
Further,
Mathews
(
1983)
found
that
the
common
murre
can
consume
several
smolts
per
day.
With
the
decrease
in
riverine
and
estuarine
habitat
quality,
increased
predation
by
avian
predators
will
occur.
Salmonids
and
avian
predators
have
co­
existed
for
thousands
of
years,
but
with
the
decrease
in
avoidance
habitat
(
e.
g.,
deep
pools
and
estuaries,
large
woody
debris,
and
undercut
banks),
avian
predation
may
play
a
role
in
the
reduction
of
some
localized
steelhead
stocks.
However,
Botkin
et
al.
(
1995)
stressed
that
overall
predation
rates
on
steelhead
should
be
considered
a
minor
factor
for
their
decline.

C.
Marine
Predation.

The
NMFS
has
noted
that
predation
by
marine
mammals
in
some
Northwest
salmonid
fisheries
has
increased
as
marine
mammal
numbers,
especially
harbor
seals
and
California
sea
lions
increased
on
the
Pacific
Coast
(
NMFS
1988).
Harvey
(
1988)
noted
that
harbor
seal
numbers
on
the
Oregon
coast
had
increased
at
a
rate
of
6
to
8.8
percent
per
year
between
1975
and
1983.

In
1990,
19.2
percent
of
the
adult
spring
and
summer
chinook
salmon
observed
in
the
Snake
River
at
Lower
Granite
Dam
exhibited
wounds
attributable
to
marine
mammals,
primarily
harbor
seals
(
Harmon
et
al.
1989).
Prior
to
1990,
injury
of
adult
salmonids
resulting
from
marine
mammal
attack
was
thought
to
be
on
the
order
of
a
few
percent
annually
(
NMFS
1988).

Botkin
et
al.
(
1995)
reported
that
marine
mammal
predation
on
anadromous
salmonid
stocks
in
southern
Oregon
and
northern
California
was
only
a
minor
factor
for
their
decline.
In
California
at
the
mouth
of
the
Russian
River,
Hanson
(
1993)
reported
that
the
foraging
behavior
of
California
sea
lions
and
harbor
seals
with
respect
to
anadromous
salmonids
was
minimal.
39
Hanson
(
1993)
also
stated
that
predation
on
salmonids
appeared
to
be
coincidental
with
the
salmonid
migrations
rather
than
dependent
upon
it.
Cooper
and
Johnson
(
1992)
reported
that
marine
mammal
predation
does
occur
on
some
local
steelhead
populations,
however,
believed
that
it
was
not
an
important
factor
in
the
decline
of
coastwide
steelhead
populations.
Although,

Roeffe
and
Mate
(
1984)
found
that
pinnipeds
fed
opportunistically
on
fast
swimming
salmonids,

less
than
1
percent
of
the
adult
Rogue
River
(
Oregon)
summer
steelhead
were
preyed
on
during
their
upriver
spawning
migration.
Therefore,
salmonids
appear
to
be
a
minor
component
of
the
diet
of
marine
mammals
(
Scheffer
and
Sperry
1931,
Jameson
and
Kenyon
1977,
Graybill
1981,

Brown
and
Mate
1983,
Roffe
and
Mate
1984,
Hanson
1993).
Principal
food
sources
of
marine
mammals
include
lampreys
(
Jameson
and
Kenyon
1977,
Roffe
and
mate
1984),
benthic
and
epibenthic
species
(
Brown
and
Mate
1983)
and
flatfish
(
Scheffer
and
Sperry
1931,
Graybill
1981).

Predation
may
significantly
influence
salmonid
abundance
in
some
local
populations
when
other
prey
are
absent
and
physical
habitat
conditions
lead
to
the
concentration
of
adult
and
juvenile
salmonids
in
small
areas
(
Cooper
and
Johnson
1992).
Pearcy
(
1992)
reviewed
several
studies
of
salmonids
off
of
the
Pacific
Northwest
coastline
and
concluded
that
salmonid
survival
was
influenced
by
the
factional
responses
of
the
predators
to
salmonids
and
alternative
prey.
Pfeifer
(
1987)
estimated
that
43
percent
of
the
steelhead
run
into
the
Lake
Washington
system,
where
there
is
a
major
fish
passage
problem,
was
lost
due
to
sea
lion
predation
during
the
1986­
87
season.
Low
flow
conditions
in
streams
can
also
enhance
predation
opportunities,
particularly
in
central
and
southern
California
streams,
where
adult
steelhead
may
congregate
at
the
mouths
of
streams
waiting
for
high
flows
for
access
(
California
Department
of
Fish
and
Game
1995).
Also,

warmer
water
temperatures
due
to
water
diversions,
water
development
and
habitat
modification
may
affect
steelhead
mortality
from
predation
directly
or
indirectly
through
stress
and
disease
associated
with
wounds
inflicted
by
pinnipeds
or
piscivorous
predators.
Several
studies
have
indicated
that
piscivorous
predators
may
control
the
abundance
and
survival
of
salmonids.
Holtby
et
al.
(
1990)
hypothesized
that
temperature­
mediated
arrival
and
predation
by
Pacific
hake
may
be
an
important
source
of
mortality
for
coho
salmon
off
of
the
west
coast
Vancouver
Island.
Beamish
et
al.
(
1992)
documented
predation
of
hatchery­
reared
chinook
and
40
coho
salmon
by
spiny
dogfish
(
Squalus
acanthias).

The
relative
impacts
of
marine
predation
on
anadromous
salmonids
are
not
well
understood,
but
most
investigators
believe
it
is
a
minor
factor
in
steelhead
declines.
However,
it
is
evident
that
anadromous
salmonids
have
historically
coexisted
with
both
marine
and
freshwater
predators
and
based
on
catch
data,
some
of
the
best
catches
of
coho,
chinook,
and
steelhead
along
the
West
Coast
of
the
United
States
occurred
after
marine
mammals,
kingfishers,
and
cormorants
were
fully
protected
by
law
(
Cooper
and
Johnson
1992).
Based
on
this,
it
would
seem
unlikely
that
in
the
absence
of
man's
intervention,
freshwater
or
marine
predators
would
extirpate
anadromous
salmonids.
Predators
play
an
important
role
in
the
ecosystem,
culling
out
unfit
individuals
thereby
strengthening
the
species
as
a
whole.
As
indicated
above,
the
increased
abundance
of
certain
predators
is
due
primarily
to
ecosystem
modification.
Therefore,
it
would
seem
more
likely
that
increased
predation
is
but
a
symptom
of
a
much
larger
problem,
namely,

habitat
modification
and
a
decrease
in
water
quantity
and
quality.

IV.
Inadequacy
of
Existing
Regulatory
Mechanisms.

A
variety
of
Federal
and
state
laws
and
measures
affect
the
abundance
and
survival
of
west
coast
steelhead
and
the
quality
of
their
habitat.
The
NMFS
has
prepared
a
separate
report
entitled
West
Coast
Steelhead
Conservation
Measures,
A
Supplement
to
the
Notice
of
Determination
for
West
Coast
Steelhead
Under
the
Endangered
Species
Act
which
summarizes
Federal,
state,

tribal
and
local
steelhead
conservation
measures.
This
report
is
available
from
the
addresses
listed
under
Summary
of
Events
Leading
to
the
Status
Review.

V.
Other
Natural
and
Manmade
Factors.

A.
Natural
Factors
1.
Drought
Drought
conditions
reduce
the
amount
of
water
available
for
all
salmonids.
Further,
during
periods
of
drought,
water
diversions
for
agriculture
and
urban
use
may
result
in
substantial
41
reduction
(
or
elimination)
of
flows
needed
for
adult
salmonid
passage,
egg
incubation,
and
juvenile
rearing
and
migration.
A
reduction
in
population
size
can
also
result
in
adverse
genetic
effects,
such
as
inbreeding
and
a
reduction
in
future
adaptation
potential.

In
the
Northwest,
annual
mean
streamflows
for
the
1977
water
year
(
October
to
September)

were
the
lowest
recorded
for
many
streams
since
the
late
nineteenth
century
(
Columbia
River
Water
Management
Group
1978).
Precipitation
levels
in
the
Snake
River
Basin
above
Ice
Harbor
Dam
also
were
below
the
25­
year
average
(
1961­
1985)
in
the
1979,
1981,
1985,
1987,

1988,
and
1990
water
years.
The
1990
water
year
became
a
fourth
consecutive
year
of
drought
condition
(
Columbia
River
Water
Management
Group
1991).
Drought
conditions
have
persisted
in
the
Columbia
River
basin
during
the
period
of
1990
to
1994.
However,
recent
weather
patterns
in
1995
have
resulted
in
above
average
rainfall
for
much
of
the
remaining
West
Coast.
California's
reservoirs
are
full
for
the
first
time
in
years,
following
severe
droughts
throughout
the
state
in
1976
to
1978
and
again
from
1986
to
1994.

Steelhead
populations
have
persisted
in
California
and
throughout
the
Pacific
Northwest
for
many
thousands
of
years
(
Behnke
1992)
despite
drastic
and
catastrophic
climate
changes,
both
long
and
short­
term.
There
are
indications
that
the
six­
year
drought
that
California
recently
experienced
may
be
a
very
mild
event
compared
to
past
droughts
(
Stine
1994).
The
key
to
survival
in
this
type
of
variable
and
rapidly
changing
environment
is
the
evolution
of
behaviors
and
life
history
traits
that
allow
steelhead
to
cope
with
a
variety
of
environmental
conditions.
A
wide
tolerance
range
is
manifested
in
a
variety
of
steelhead
behaviors
and
life
history
traits
relative
to
other
Pacific
salmon.
This
suggests
steelhead
populations
(
coastal
and
inland
forms)

possess
the
ability
to
survive
in,
and
adapt
to,
the
unique
environments
throughout
the
species
range
Although
natural
events
may
have
harmful
effects
on
species
or
populations,
anthropogenic
impacts
on
fish
habitat
may
be
the
final
factor
that
determines
the
ability
of
these
populations
to
persist.
Populations
that
are
fragmented
and/
or
reduced
in
size
and
range
are
more
vulnerable
to
extirpation
by
natural
events.
At
this
time
it
is
not
clear
whether
recent
climatic
conditions
42
represent
a
long­
term
change
which
will
continue
to
affect
salmonid
stocks
or
whether
these
changes
are
short­
term
environmental
fluctuations
that
can
be
expected
to
reverse
in
the
near
future.
Many
of
the
steelhead
population
declines
began
prior
to
these
recent
drought
conditions.
Humans
have
little
control
of
the
oceanic
or
atmospheric
cycles;
therefore,
it
is
important
to
minimize
anthropogenic
effects
on
protecting
anadromous
salmonid
habitat
in
streams,
rivers,
and
estuaries
in
order
to
buffer
salmonid
populations
against
these
natural
cycles.

2.
Floods
During
flood
events,
land
disturbances
resulting
from
logging,
road
construction,
mining,

urbanization,
livestock
grazing,
agriculture,
fire,
and
other
uses
may
contribute
sediment
directly
to
streams
or
exacerbate
sedimentation
from
natural
erosive
processes
(
California
Advisory
Committee
on
Salmon
and
Steelhead
Trout
1988,
California
State
Lands
Commission
1993,

Forest
Ecosystem
Management
Assessment
Team
1993).
Sedimentation
of
stream
beds
has
been
implicated
as
a
principle
cause
of
declining
salmonid
populations
through­
out
their
range.

Judsen
and
Ritter
(
1964),
the
California
Department
of
Water
Resources
(
1982b),
and
the
California
States
Lands
Commission
(
1993)
have
stated
that
northwestern
and
central
coastal
California
have
some
the
most
erodible
terrain
in
the
world.
Many
of
the
parent
soil
materials
present
in
this
area
are
extremely
steepened
and
are
prone
to
flooding
and
landslides
(
California
Department
of
Water
Resources
1982a).
Several
studies
have
indicated
that
in
this
region,

catastrophic
erosion
and
subsequent
stream
sedimentation
(
such
as
during
the
1955
and
1964
floods)
resulted
from
areas
which
had
been
clearcut
or
which
had
roads
constructed
on
unstable
soils
(
Janda
et
al.
1975,
Wahrhaftig
1976,
Kelsey
1980,
Lisle
1982,
Hagans
et
al.
1986).
In
addition
to
problems
associated
with
sedimentation,
flooding
can
cause
scour
and
redeposition
of
spawning
gravels
in
typically
inaccessible
areas.

As
streams
and
pools
fill
in
with
sediment,
flood
flow
capacity
is
reduced.
Such
changes
cause
decreased
stream
stability
and
increased
bank
erosion,
and
subsequently
exacerbate
existing
sedimentation
problems
(
Lisle
1982).
All
of
these
sources
contribute
to
the
sedimentation
of
spawning
gravels
and
filling
of
pools
and
estuaries
used
by
all
anadromous
salmonids.
Channel
43
widening
and
loss
of
pool­
riffle
sequence
due
to
aggradation
has
damaged
spawning
and
rearing
habitat
of
all
salmonids.
By
1980,
the
pool­
riffle
sequence
and
pool
quality
in
some
northern
California
and
southern
Oregon
streams
still
had
not
fully
recovered
from
the
1964
regional
flood.
In
fact,
Lisle
(
1982)
found
that
many
north
coast
streams
continue
to
show
signs
of
harboring
debris
flow.
Such
streams
have
remained
shallow,
wide,
warm,
and
unstable
since
these
floods.

3.
Ocean
Conditions
When
steelhead
smolts
from
North
America
enter
the
Pacific
Ocean
they
begin
a
directed
movement
into
offshore
waters
of
the
Gulf
of
Alaska
(
Light
et
al.
1988).
Steelhead
seem
to
generally
follow
a
counter
clockwise
migration
pattern
in
epipelagic
waters
east
of
167
E
East
longitude
(
Light
et
al.
1988),
primarily
within
27
feet
(
8.2
meters)
of
the
water
surface,
but
have
been
captured
at
depths
of
62
feet
(
18.9
meters)
(
Light
et
al.
1989,
Burgner
et
al.
1992).
The
northern
limit
of
steelhead
migration
in
the
ocean
extends
slightly
north
of
the
Aleutian
islands
and
is
closely
associated
with
the
41
E
F
(
5
E
C)
sea
surface
isotherm,
while
the
southern
limit
of
steelhead
migration
and
rearing
is
approximately
39
E
North
latitude
and
is
closely
associated
with
the
59
E
F
(
15
E
C)
sea
surface
isotherm
(
Light
et
al.
1989,
Pearcy
1992,
Burgner
et
al.

1992).
Burgner
et
al.
(
1992)
reported
that
coastal
Oregon
and
California
steelhead
stocks
may
have
more
restricted
westward
migrations
than
do
more
northerly
stocks.

Steelhead
stocks
are
widely
dispersed
from
California
to
Alaska
and
are
extensively
intermingled
(
Light
et
al.
1989,
Pearcy
1992).
The
North
Pacific
Fisheries
Commission
(
INPFC)
trapped,

disc­
tagged,
and
released
1,722
adult
steelhead
in
the
open
ocean
from
1956
to
1988
during
their
high
seas
tagging
experiments.
Of
these
1,722
tagged
steelhead,
77
were
recovered
in
North
American
coastal
areas
or
spawning
rivers
(
Burgner
et
al.
1992).
Of
the
77
North
American
steelhead
returns,
22
were
recovered
in
British
Columbia
streams,
15
were
recovered
in
coastal
Washington
and
Puget
Sound
streams,
19
were
recovered
in
the
Columbia
River
and
tributaries,
12
were
recovered
from
coastal
Oregon
streams
and
nine
were
recovered
in
California
streams
from
the
Carmel
River
in
central
California
north
to
Crescent
City
(
Burgner
44
et
al.
1992).
Ocean
migration
and
distribution
of
southern
California
steelhead
populations
are
unknown.
There
have
not
been
any
tagging
studies
conducted
on
populations
in
southern
streams
to
evaluate
ocean
distribution.
Further,
no
steelhead
tagged
on
the
high
seas
have
been
recovered
in
these
California
streams
(
McEwan
and
Jackson
1996).

Large
fluctuations
in
Pacific
salmon
catch
have
occurred
during
the
past
century.
Annual
world
harvest
of
Pacific
salmon
has
varied
from
347
million
pounds
(
lbs)
(
772
million
kg)
in
the
1930s
to
about
184
million
lbs
(
409
million
kg)
in
1977
and
back
to
368
million
lbs
(
818
million
kg)
by
1989
(
Hare
and
Francis
1993).
Mechanisms
linking
atmospheric
and
oceanic
conditions
to
fish
population
survivorship
and
production
have
been
suggested
for
stocks
in
general
(
Shepherd
et
al.
1984)
and
for
Pacific
salmon
specifically
(
Rogers
1984,
Nickelson
1986,
Johnson
1988,

Brodeur
and
Ware
1992,
Francis
et
al.
1992,
Francis
1993,
Hare
and
Francis
1993,
Ward
1993).

Vernon
(
1958),
Holtby
and
Scrivener
(
1989),
and
Holtby
et
al.
(
1990)
have
reported
associations
between
salmon
survival
during
the
first
few
months
at
sea
and
ocean
conditions
such
as
sea
surface
temperature
and
salinity.
Some
studies
have
tried
to
link
salmon
production
to
oceanic
and
atmospheric
climate
change.
For
example,
Beamish
and
Bouillon
(
1993)
and
Ward
(
1993)
found
that
trends
in
Pacific
salmon
catches
were
similar
to
trends
in
winter
atmospheric
circulation
in
the
North
Pacific.

The
Subarctic
Front,
the
most
prominent
feature
of
the
North
Pacific
Transitional
Region,
plays
a
role
in
the
definition
of
the
major
physical
and
biological
domains
in
the
Northeast
Pacific
Ocean.
It
is
possible
that
changes
in
the
location
or
structure
of
the
Subarctic
Front
may
affect
any
of
the
physical
and
biological
gradients
in
this
area
(
Pearcy
1991).
McGowan
(
1986)

reported
that
Subarctic
Frontal
dynamics
influence
forage
aggregations
and
lead
to
higher
biological
productivity
which
impacts
salmonid
species
at
higher
trophic
levels.
Furthermore,

variability
in
the
Subarctic
Front
may
affect
other
physical
features
which
alter
productivity,
both
in
the
Central
Subarctic
Domain
and
downstream
in
the
coastal
domains
(
Reid
1962,
Wickett
1967,
Eber
1971,
Favorite
and
McLain
1973,
Colebrook
1977,
Chelton
et
al.
1982a
and
1982b,

Fulton
and
LeBrasseur
1985,
Ware
and
McFarlane
1989).
Although
the
Subarctic
Front
can
be
analytically
defined,
its
structure
changes
in
both
space
(
White
1982,
Levine
and
White
1983)
45
and
time
(
White
et
al.
1980).
It
moves,
intensifies,
decays,
and
undergoes
seasonal
changes
(
Roden
1977).

The
influence
of
Subarctic
Frontal
dynamics
on
salmonids
is
probably
caused
by
indirect
trophic
interactions
rather
than
a
direct
cause­
effect
relationship
(
Pearcy
1992).
The
interaction
or
population
control
might
be
"
bottom­
up"
by
lower
trophic
levels,
or
"
top­
down"
by
predators.

This
is
especially
true
for
prey
organisms
including
phytoplankton,
zooplankton,
cephalopods,

and
fish
(
Pearcy
et
al.
1988),
as
well
as
predatory
organisms
including
marine
mammals
and
sea
birds
(
Rogers
1984).
Pearcy
(
1992)
suggests
that
predatorial
response
to
coho
smolt
and
alternative
prey
availability
could
influence
prey
survival
rates.
This
is
especially
important
during
years
of
high
upwelling
resulting
in
greater
smolt
dispersal
and
alternative
prey
availability.
Several
studies
have
examined
the
possibility
that
salmonid
production
or
survival
is
indirectly
related
to
primary
production.
For
example,
Pearcy
and
Fisher
(
1988)
linked
salmon
abundance
with
coastal
chlorophyll
concentrations,
primary
production,
and
upwelling.

A
feature
common
to
many
studies
of
biological
production
is
the
identification
of
high
or
low
periods
of
abundance
for
the
study
organism.
Shifts
in
abundance
for
many
organisms
appear
to
have
coincided
with
the
shift
in
abundance
of
salmon
in
the
late
1970s
(
Rogers
1984).
Hare
and
Francis
(
1993)
identified
two
interventions
(
statically
significant
changes
in
the
mean
of
a
time
series)
in
the
abundance
of
Alaskan
pink
and
sockeye
salmon
between
1919
and
1988:
one
occurring
in
the
late
1970s
and
the
other
occurring
in
the
early
1950s.
The
intervention
(
increase)
in
the
late
1970s
was
more
pronounced
than
the
earlier
intervention
(
decrease)
and
matches
well
with
the
shift
noted
by
Rogers
(
1984)
and
Ward
(
1993).
Also,
the
timing
of
the
1970s
intervention
has
often
been
correlated
to
change
in
the
abundance
of
other
organisms.

Brodeur
and
Ware
(
1992)
found
that
the
abundance
of
zooplankton,
several
species
of
fish,
and
cephalopods
in
the
central
Subarctic
Gyre
changed
significantly
from
the
period
of
1956­
1962
to
1980­
1989.
These
changes
corresponded
to
a
1.7
fold
increase
in
the
estimated
biomass
of
all
North
American
salmon
combined
between
the
periods
of
1956­
1962
and
1980­
1984
(
Rodgers
1987).
46
Francis
and
Sibley
(
1991)
and
Francis
et
al.
(
1992)
have
developed
a
model
linking
decadal­
scale
atmospheric
variability
to
salmon
production
hypotheses
developed
by
Hollowed
and
Wooster
(
1991)
and
Wickett
(
1967),
as
well
as
evidence
presented
in
many
other
studies.
This
model
describes
a
time
series
of
biological
and
physical
variables
from
the
Northeast
Pacific
which
appear
to
share
decadal­
scale
patterns;
most
notably
synchronous
shifts
in
mean
conditions
during
the
late
1970s
and
out­
of­
phase
relationship
between
variables
in
the
Coastal
Upwelling
and
Coastal
Downwelling
domains.
Biological
and
physical
variables
which
appear
to
have
undergone
shifts
during
the
late
1970s
include
the
following:
salmon
(
Rogers
1984,
1987,
Hare
and
Francis
1993)
and
other
pelagic
fish,
cephalopods,
and
zooplankton
(
Brodeur
and
Ware
1992);
oceanographic
properties
such
as
current
transport
(
Royer
1989),
sea
surface
temperature
and
upwelling
(
Holowed
and
Wooster
1991);
and
atmospheric
phenomena
such
as
atmospheric
circulation
patterns,
sea­
surface
pressure
patterns,
and
sea­
surface
wind­
stress
(
Trenberth
1990,
Trenberth
et
al.
1993).
Variables
from
the
Coastal
domains
which
appear
to
fluctuate
out­
of­
phase
include
salmon
(
Francis
and
Sibley
1991),
current
transport
(
Wickett
1967,
Chelton
1983),
sea
surface
temperature
and
upwelling
(
Tabata
1984,
Hollowed
and
Wooster
1991),
and
zooplankton
(
Wickett
1967).

Finally,
Scarnecchia
(
1981)
reported
that
near­
shore
conditions
during
the
spring
and
summer
months
along
the
California
coast
may
dramatically
affect
year­
class
strength
of
salmonids.

Bottom
et
al.
(
1986)
believed
that
coho
salmon
along
the
Oregon
and
California
coasts
may
be
especially
sensitive
to
upwelling
patterns
because
these
regions
lack
extensive
bays,
straits,
and
estuaries
which
could
buffer
adverse
oceanographic
effects
such
as
those
found
along
the
Washington,
British
Columbia,
and
Alaskan
coasts.
The
paucity
of
high
quality,
near­
shore
habitat
coupled
with
variable
ocean
conditions
have
served
to
make
freshwater
habitat
more
crucial
for
the
survival
and
persistence
of
many
steelhead
populations.

a.
El
Niño
"
El
Niño"
an
environmental
condition
often
cited
as
a
cause
for
the
decline
of
west
coast
salmonids.
El
Niño
is
an
unusual
warming
of
the
Pacific
Ocean
off
South
America
and
is
caused
by
atmospheric
changes
in
the
tropical
Pacific
Ocean
(
Southern
Oscillation­
ENSO).
El
Niño
47
events
occur
when
there
is
a
decrease
in
the
surface
atmospheric
pressure
gradient
from
the
normal­
steady
trade
winds
that
blow
across
the
ocean
from
east
to
west
on
both
sides
of
the
equator.
There
is
a
drop
in
pressure
in
the
east
off
South
America
and
a
rise
in
the
pressure
in
the
western
Pacific.
The
resulting
decrease
in
the
pressure
gradient
across
the
Pacific
Ocean
causes
the
easterly
trade
winds
to
relax,
and
even
reverse
in
some
years.
When
the
trade
winds
weaken,
sea
level
in
the
western
Pacific
Ocean
drops,
and
a
plume
of
warm
sea
water
flows
from
west
to
east
toward
South
America,
eventually
reaching
the
coast
where
it
is
reflected
south
and
north
along
the
continents.

El
Niño
ocean
conditions
are
characterized
by
anomalous
warm
sea
surface
temperatures
and
changes
coastal
currents
and
upwelling.
Principal
ecosystem
alterations
include
decreased
primary
and
secondary
productivity
and
changes
in
prey
and
predator
species
distributions.

Several
recent
El
Niño
events
have
been
recorded
during
the
last
several
decades,
including
those
of
1940­
41,
1957­
58,
1982­
83,
1986­
87,
1991­
1992,
and
93­
94.

Anadromous
salmonids
have
managed
to
persist
in
the
face
of
numerous
climatic
events
and
changes.
The
long­
term
persistence
of
steelhead
populations
depends
on
their
ability
to
withstand
fluctuations
in
environmental
conditions.
It
is
apparent
that
the
tremendous
loss
of
freshwater
habitat
combined
with
extremely
small
population
levels
cause
salmonid
populations
to
be
more
vulnerable
to
extirpation
from
natural
events.
Until
recently,
when
salmonid
population
levels
have
reached
critical
levels,
these
environmental
conditions
have
largely
gone
unnoticed
(
Lawson
1993).
Therefore,
it
would
seem
that
environmental
events
and
their
impacts
on
remaining
populations,
serve
more
as
an
indication
of
unstable
population
levels
rather
than
a
direct
cause
of
a
decline.

4.
Other
Natural
Occurrences
The
eruption
of
Mount
St.
Helens
in
1980
resulted
in
devastating
impacts
to
nearby
rivers
and
streams.
Impacts
have
included
high
sedimentation
in
spawning
and
rearing
areas,
resulting
in
stock
displacement
to
various
tributaries
(
Leider
1989),
increased
water
temperature,
and
decreased
fish
foraging
efficiency
(
Palmisano
et
al.
1993).
48
Wildfires
are
also
a
factor
which
can
contribute
to
an
increase
in
short­
term
sediment
runoff
(
Wells
1987).
In
addition,
water
quality
degradation
can
result
from
chemical
agents
used
to
control
forest
fires
(
U.
S.
Forest
Service
1993).

B.
Manmade
Factors
1.
Artificial
Propagation
In
1993,
over
81
million
juvenile
salmonid
hatchery
fish
were
released
into
the
Snake
and
Columbia
River
system
above
Bonneville
Dam
(
Columbia
Basin
Fish
and
Wildlife
Authority
1994).
Juvenile
steelhead
have
accounted
for
about
15
percent
of
these
releases,
or
about
12
million
juveniles
(
Columbia
Basin
Fish
and
Wildlife
Authority
1994).
Juvenile
steelhead
hatchery
releases
average
about
2.5
million
below
Bonneville
Dam
since
1987
(
Columbia
Basin
Fish
and
Wildlife
Authority
1994).
The
Snake
River
system
has
accounted
for
the
majority
of
steelhead
hatchery
production
in
areas
above
Bonneville
Dam,
averaging
about
5
million
juveniles
per
year
since
1980
(
Columbia
Basin
Fish
and
Wildlife
Authority
1994).
During
the
period
from
1978
to
1987,
the
following
steelhead
hatchery
production
occurred
in
the
western
United
States:
Washington
at
6,782,000,
Idaho
at
5,372,000,
Oregon
at
4,537,000,
California
at
2,304,000,
and
Alaska
at
62,000
fish
per
year
(
Light
1987).
A
total
of
24,605,000
steelhead
smolts
on
average
are
produced
each
year
in
these
four
western
states.

Non­
native
steelhead
stocks
have
historically
been
introduced
as
broodstock
in
hatcheries
and
widely
transplanted
in
many
coastal
rivers
and
streams.
Altukhov
and
Salmenkova
(
1986)
have
shown
that
anadromous
salmonids
transferred
to
other
watersheds
rarely
persist
for
more
than
two
generations
without
repeated
artificial
propagation.
Withler
(
1982)
showed
that
there
has
been
no
successful
case
of
establishing
a
new
run
of
anadromous
salmonids
by
transplanting
stocks
anywhere
along
the
Pacific
Coast.
Fisheries
agencies
within
the
states
of
Washington,

Oregon,
Idaho
and
California,
along
with
other
organizations,
have
transplanted
non­
native
steelhead
stocks
throughout
their
respective
states
within
this
past
century
(
Bryant
1994,
Busby
et
al.
1996).

Many
concerns
exist
regarding
the
impacts
of
artificial
propagation
on
wild
stocks
of
salmon.
49
Competition
which
can
occur
among
hatchery
and
native
adults
for
spawning
sites
and
food,

may
lead
to
decreased
production.
Hatchery
may
outnumber
wild
fish
and
monopolize
available
spawning
habitat
when
wild
stocks
are
small
and
hatchery
supplementation
occurs.
Fleming
and
Gross
(
1992)
stated
that
the
negative
effect
of
such
competition
can
be
magnified
by
the
fact
that
naturally
spawning
hatchery
stocks
have
lower
spawning
success
than
do
wild
fish.

Steward
and
Bjornn
(
1990)
found
that
hatchery
stocks
may
also
produce
fewer
smolts
and
returning
adults.
Nielsen
(
1994)
found
the
introduction
of
hatchery
reared
coho
salmon
into
the
Noyo
River,
California,
led
to
displacement
of
wild
cohorts
from
their
usual
microhabitats
and
shifts
in
their
foraging
behavior.
Stempel
(
1988)
concluded
that
competition
might
be
occurring
in
the
mainstem
of
the
Klamath
and
Trinity
rivers
among
hatchery
and
wild
salmonids,
resulting
in
low
survival
of
both.

Juvenile
steelhead
which
have
been
derived
from
non­
native,
hatchery
broodstock
may
stray
and
interact
with
native
populations.
Altukhov
and
Salmenkova
(
1986)
reported
that
when
nonnative
hatchery
strays
spawn
in
the
wild,
young
fish
with
some
non­
native
genes
may
result.

Studies
conducted
in
areas
of
the
Pacific
Coast
have
found
that
juvenile
salmonids
produced
from
stray
hatchery
fish
and
hatchery­
wild
hybrids
have
relatively
low
survival
rates
compared
to
native
fish
(
Chilcote
et
al.
1986,
Riesenbichler
and
McIntyre
1977).
Waples
(
1991),
Hindar
et
al.
(
1991),
and
Steward
and
Bjornn
(
1990)
found
that
the
impact
of
stock
transfers
increases
dramatically
if
non­
native
salmonids
are
planted
on
top
of
wild
populations
for
several
generations.
When
this
method
of
transfer
occurs,
Altukhov
and
Salmenkova
(
1986)
found
a
loss
of
local
adaptations
which
may
lead
to
extirpation
of
that
local
stock.

Genetic
changes
in
hatchery
stocks
of
Pacific
salmonids
have
been
documented
and
models
have
recently
been
constructed
by
Waples
(
1990a,
b)
and
Waples
and
Teel
(
1990)
to
aid
in
understanding
the
consequences
of
these
changes.
Steward
and
Bjornn
(
1990)
noted
that
large
differences
in
the
genetic
structure
of
wild
and
hatchery
stocks
may
potentially
lead
to
lower
survival
rates.
Steward
and
Bjornn
(
1990)
also
reported
that
supplementation
with
hatchery
stocks
can
have
differing
effects
depending
on
the
size
of
the
wild
population.
Shapovalov
and
Taft
(
1954)
noted
an
inverse
correlation
between
the
number
of
downstream
migrants
and
adult
50
returns,
implying
that
low
intraspecific
competition
increases
oceanic
survivorship
of
downstream
migrants.

Crowded
conditions
in
hatcheries
can
create
favorable
environments
for
many
disease
organisms.
Introduction
of
exotic
stocks
can
also
introduce
a
new
disease
into
a
wild
population.
The
ability
of
a
wild
stock
to
cope
with
an
introduced
disease
is
reduced
if
the
stock's
genetic
variability
has
been
reduced
through
selection
or
genetic
drift
(
Allendorf
and
Phelps
1980).

The
capture
of
broodstock
may
also
adversely
impact
small
or
declining
wild
populations
due
to
pre­
spawning
mortality
during
capture
or
transport,
differential
viability
of
gametes
in
artificial
situations,
disease,
and
artificial
selection.
Verspoor
(
1988)
noted
that
wild
broodstock
typically
contribute
little
genetic
diversity
to
subsequent
generations
of
hatchery
fish.
Taking
more
wild
fish
for
broodstock
in
an
attempt
to
overcome
these
problems
in
hatchery
stocks
may
ultimately
increase
risks
to
wild
populations.

The
relatively
low
number
of
spawners
needed
to
sustain
a
hatchery
population
can
result
in
high
harvest­
to­
escapement
ratios
in
waters
where
regulations
are
set
according
to
hatchery
production.
This
practice
can
lead
to
over­
exploitation
and
reduction
in
size
of
wild
populations
coexisting
in
the
same
system.
For
example,
in
a
declared
"
hatchery
management
area"
in
British
Columbia,
harvest
rates
on
coho
salmon
are
as
high
as
95
percent
(
Hilborn
1992).
This
is
sustainable
only
because
of
the
most
successful
hatchery
stocks,
and,
as
a
result,
wild
stocks
have
declined
(
Hilborn
1992).

Available
research
indicates
that
interactions
between
non­
native
and
wild
stocks
may
have
contributed
to
the
decline
of
this
species
across
its
range.
More
recent
hatchery
practices,
such
as
utilizing
native
broodstocks
and
limiting
native
and
hatchery
fish
interactions
through
temporal
or
geographic
means,
may
reduce
negative
impacts
to
wild
stocks.
However,

hatcheries
may
palliate
the
widespread
loss
and
destruction
of
habitat,
concealing
the
real
problems
facing
anadromous
resources
(
Goodman
1990,
Hilborn
1992,
Meffe
1992).
51
Summary
Steelhead
on
the
west
coast
of
the
United
States
have
experienced
dramatic
declines
in
abundance
during
the
past
several
decades
as
a
result
of
human­
induced
and
natural
factors.

The
scientific
literature
is
replete
with
information
documenting
the
decline
of
steelhead
populations
and
anadromous
salmonid
habitats.
There
is
no
single
factor
solely
responsible
for
this
decline.
Every
factor
identified
in
this
report
has
contributed
in
varying
degree
to
this
decline.
Given
the
complexity
of
this
species'
life
history
and
the
ecosystem
in
which
it
resides,

the
authors
believe
it
is
impossible
to
accurately
quantify
the
relative
contribution
of
any
one
factor
to
the
decline
of
a
given
steelhead
ESU.
Rather,
the
authors
have
found
it
only
possible
to
highlight
those
factors
which
have
significantly
affected
the
status
of
a
particular
ESU
(
Table
1).
This
list
will
expand
and
contract
as
more
information
becomes
available.
It
is
important
to
note
in
reviewing
this
list
that
recovery
efforts
must
focus
on
those
areas
which
are
within
human
influence
and
control.

Water
storage,
withdrawal,
conveyance,
and
diversions
for
agriculture,
flood
control,
domestic,

and
hydropower
purposes
have
greatly
reduced
or
eliminated
historically
accessible
habitat.

Modification
of
natural
flow
regimes
have
resulted
in
increased
water
temperatures,
changes
in
fish
community
structures,
depleted
flows
necessary
for
migration,
spawning,
rearing,
flushing
of
sediments
from
spawning
gravels,
gravel
recruitment
and
transport
of
large
woody
debris.

Physical
features
of
dams,
such
as
turbines
and
sluiceways,
have
resulted
in
increased
mortality
of
both
adults
and
juvenile
salmonids.
Attempts
to
mitigate
adverse
impacts
of
these
structures
have
to
date
met
with
limited
success.

Natural
resource
use
and
extraction
leading
to
habitat
modification
can
have
significant
direct
and
indirect
impacts
to
steelhead
populations.
Land
use
activities
associated
with
logging,
road
construction,
urban
development,
mining,
agriculture,
and
recreation
have
significantly
altered
fish
habitat
quantity
and
quality.
Associated
impacts
of
these
activities
include:
alteration
of
streambank
and
channel
morphology;
alteration
of
ambient
stream
water
temperatures;

degradation
of
water
quality;
elimination
of
spawning
and
rearing
habitat;
fragmentation
of
available
habitats;
elimination
of
downstream
recruitment
of
spawning
gravels
and
large
woody
52
debris;
removal
of
riparian
vegetation
resulting
in
increased
stream
bank
erosion;
and
increased
sedimentation
input
into
spawning
and
rearing
areas
resulting
in
the
loss
of
channel
complexity,

pool
habitat,
suitable
gravel
substrate,
and
large
woody
debris.
Studies
indicate
that
in
most
western
states,
about
80
to
90
percent
of
the
historic
riparian
habitat
has
been
eliminated.

Further,
it
has
been
estimated
that
during
the
last
200
years,
the
lower
48
United
States
have
lost
approximately
53
percent
of
all
wetlands.
Washington
and
Oregon's
wetlands
have
been
estimated
to
have
diminished
by
one
third,
while
it
is
estimated
that
California
has
experienced
a
91
percent
loss
of
its
wetland
habitat.

The
degree
of
spatial
and
temporal
connectivity
between
and
within
watersheds
is
an
important
consideration
for
maintaining
aquatic
riparian
ecosystem
functions
is.
Loss
of
this
connectivity
and
complexity,
such
as
the
loss
of
deep
pool
habitats,
has
contributed
to
the
decline
of
steelhead.
In
Washington,
the
number
of
large,
deep
pools
in
National
Forest
streams
has
decreased
by
as
much
as
58
percent
due
to
sedimentation
and
loss
of
pool­
forming
structures
such
as
boulders
and
large
wood.
Similarly,
in
Oregon,
the
abundance
of
large,
deep
pools
on
private
coastal
lands
has
decreased
by
as
much
as
80
percent.

Steelhead
have
been,
and
continue
to
be,
an
important
recreational
fishery
throughout
their
range.
During
periods
of
decreased
habitat
availability,
the
impacts
of
recreational
fishing
on
native
anadromous
stocks
may
be
heightened.
While
not
generally
targeted
in
commercial
fisheries
in
the
ocean,
high
seas
driftnet
fishing
may
have
been
partially
responsible
for
declines
in
steelhead
abundance.
Research
has
estimated
that
unauthorized
high
seas
driftnet
fisheries
may
have
harvested
between
2
and
28
percent
of
the
steelhead
that
were
destined
to
return
to
the
Pacific
coast
of
North
America.
However,
such
fisheries
cannot
account
for
the
total
declines
in
steelhead
abundance
observed
in
North
America.

Introduction
of
non­
native
species
and
modification
of
habitat
have
resulted
in
increased
predator
populations
and
salmonid
predation
in
numerous
river
systems.
Marine
predation
is
also
of
concern
in
some
areas
given
the
dwindling
steelhead
run­
size
in
recent
years.
In
general,

predation
rates
on
steelhead
are
considered
by
most
investigators
to
be
an
insignificant
53
contribution
to
the
large
declines
observed
in
west
coast
populations.
However,
predation
may
significantly
influence
salmonid
abundance
in
some
local
populations
when
other
prey
are
absent
and
physical
habitat
conditions
lead
to
the
concentration
of
adults
and
juveniles.

Natural
environmental
conditions
have
served
to
exacerbate
the
problems
associated
with
degraded
and
altered
riverine
and
estuarine
habitats.
Recent
floods
and
persistent
drought
conditions
have
reduced
already
limited
spawning,
rearing,
and
migration
habitat.
Furthermore,

climatic
conditions
appear
to
have
resulted
in
decreased
ocean
productivity
which
may
help
offset
degraded
freshwater
habitat
conditions
to
some
degree.
Environmental
conditions
such
as
these
have
gone
largely
unnoticed
until
recently,
when
salmonid
populations
have
reached
critical
low
levels.

In
an
attempt
to
mitigate
for
lost
habitat
and
reduced
fisheries,
extensive
hatchery
programs
have
been
implemented
throughout
the
range
of
steelhead
on
the
West
Coast.
While
some
of
these
programs
have
been
successful
in
providing
fishing
opportunities,
the
impacts
of
these
programs
on
wild
stocks
are
not
well
understood.
Competition,
genetic
introgression,
and
disease
transmission
resulting
from
hatchery
introductions
may
significantly
impact
the
production
and
survival
of
wild
steelhead.
Furthermore,
displacement
of
wild
fish
for
broodstock
purposes
may
result
in
additional
negative
impacts
to
small
or
dwindling
natural
populations.
It
is
important
to
note
however
that
the
use
of
hatcheries
will
likely
play
an
important
role
in
reestablishing
depressed
stocks
of
Pacific
salmonids.
Alternative
uses
of
supplementation,
such
as
for
the
creation
of
terminal
fisheries,
must
be
fully
explored
to
limit
negative
impacts
to
remaining
wild
populations.
This
use
must
be
tempered
with
the
understanding
that
protection
of
wild
fish
and
their
habitats
is
critical
to
maintaining
healthy,

fully­
functioning
ecosystems.

Authors
The
primary
authors
of
this
report
were
Gregory
J.
Bryant,
Fishery
Biologist,
National
Marine
Fisheries
Service,
Southwest
Region,
and
Jim
Lynch,
Fishery
Biologist,
National
Marine
Fisheries
Service,
Northwest
Region.
54
Table
1.
Summary
of
Factors
Affecting
Each
Steelhead
ESU
Name
of
ESU
Geographic
Range
of
ESU
Factors
Affecting
ESU
1)
Puget
Sound
Strait
of
Juan
De
Fuca,
Puget
Sound,
and
Hood
Canal,
WA.
!
Habitat
blockages
!
Hatchery
introgression
!
Urbanization
!
Logging
!
Hydropower
development
!
Harvest
2)
Olympic
Peninsula
West
of
Elwha
River
and
south
to,
but
not
including,
Grays
Harbor
drainage,
WA.
!
Hatchery
introgression
!
Logging
!
Minor
habitat
blockages
!
Hydropower
development
!
Harvest
3)
Southwest
Washington
Grays
Harbor
drainage,
WA
to
Columbia
River
below
Cowlitz
River,
WA
and
below
Willamette
River,
OR.
!
Hatchery
introgression
!
Logging
!
Agriculture
!
Harvest
!
Hydropower
!
Predation
4)
Lower
Columbia
River
Columbia
River
and
tributaries
between
Cowlitz
and
Wind
Rivers
in
WA,
Willamette
and
Hood
Rivers
in
OR.
!
Hatchery
introgression
!
Habitat
blockages
!
Logging
!
Eruption
of
Mt.
Saint
Helens
!
Hydropower
development
!
Predation
!
Harvest
5)
Upper
Willamette
River
Willamette
River,
OR
upstream
from
Willamette
Falls.
!
Urbanization
!
Logging
!
Habitat
blockages
!
Predation
!
Agriculture
!
Harvest
6)
Oregon
Coast
Oregon
coast
north
of
Cape
Blanco,
OR
excluding
Columbia
River
tributaries.
!
Logging
!
Hatchery
introgression
!
Agriculture
!
Minor
habitat
blockages
!
Historic
flooding
!
Harvest
55
Table
1.
Summary
of
Factors
Affecting
Each
Steelhead
ESU
(
continued)

Name
of
ESU
Geographic
Range
of
ESU
Factors
Affecting
ESU
7)
Klamath
Mountains
Province
Elk
River,
OR
to
Klamath
and
Trinity
Rivers
in
CA.
!
Hatchery
introgression
!
Logging
!
Water
diversion\
extraction
!
Habitat
blockages
!
Poaching
!
Agriculture
!
Hydropower
development
!
Historic
flooding
!
Mining
8)
Northern
California
Redwood
Creek,
Humboldt
County,
CA
to
Gualala
River,
CA.
!
Historic
Flooding
!
Predation
!
Water
diversion\
extraction
!
Minor
habitat
blockages
!
Poaching
!
Logging
!
Agriculture
!
Mining
9)
Central
California
Coast
Russian
River,
CA
to
Soquel
Creek
and
the
drainages
of
San
Francisco
and
San
Pablo
Bays,
CA;
excluded
is
the
Sacramento/
San
Joaquin
River
Basin.
!
Water
diversion\
extraction
!
Habitat
blockages
!
Agriculture
!
Logging
!
Historic
flooding
!
Hatchery
introgression
!
Poaching
!
Mining
!
Urban
development
!
Harvest
10)
South/
Central
California
Coast
Pajaro
River,
CA
to
north
of
the
Santa
Maria
River,
CA.
!
Urbanization
!
Water
diversion\
extraction
!
Historic
flooding
!
Habitat
blockages
!
Agriculture
!
Poaching
!
Harvest
11)
Southern
California
Santa
Maria
River,
CA
to
southern
extent
of
species
range.
!
Water
diversion\
extraction
!
Habitat
blockages
!
Urbanization
!
Agriculture
!
Harvest
56
Table
1.
Summary
of
Factors
Affecting
Each
Steelhead
ESU
(
continued)

Name
of
ESU
Geographic
Range
of
ESU
Factors
Affecting
ESU
12)
Central
Valley
Sacramento
River,
CA
and
San
Joaquin
River,
CA.
!
Water
diversion\
extraction
!
Mining
!
Agriculture
!
Urbanization
!
Habitat
blockages
!
Logging
!
Harvest
!
Hydropower
development
!
Hatchery
introgression
13)
Middle
Columbia
River
Basin
Mosier
Creek,
OR
to
the
Yakima
River,
WA
inclusive.
!
Water
diversion\
extraction
!
Hydropower
development
!
Agriculture
!
Hatchery
introgression
!
Predation
!
Harvest
14)
Upper
Columbia
River
Basin
Columbia
River
upstream
from
Yakima
River,
WA.
!
Hydropower
development
!
Water
diversion\
extraction
!
Agriculture
!
Hatchery
introgression
!
Predation
!
Harvest
15)
Snake
River
Basin
Snake
River
Basin,
ID,
upstream
from
confluence
with
Columbia
River.
!
Logging
!
Agriculture
!
Hydropower
development
!
Water
diversion\
extraction
!
Hatchery
introgression
!
Habitat
blockages
!
Mining
!
Harvest
57
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Appendix
A.
Impacts
of
sedimentation
on
aquatic
ecosystems
(
Koski
and
Walter
1978)

I.
Inorganic
Sediment
Input
A.
Changes
in
salmonid
spawning
habitat
1.
Suffocation
of
eggs
and
alevins
2.
Blockage
of
fry
emergence
3.
Change
in
timing
of
fry
emergence
4.
Reduction
of
size
of
fry
at
emergence
5.
Interference
with
homing
ability
of
adults
B.
Changes
in
salmonid
rearing
habitat
1.
Reduction
in
living
space
and
shelter
2.
Change
in
food
availability
3.
Increase
in
emigration
C.
Changes
affecting
macroinvertebrates
1.
Reduction
in
living
space
around
rocks
2.
Reduction
in
food
(
periphyton)
3.
Increase
in
drift
rate
4.
Prevention
of
larval
development
and
emergence
D.
Changes
affecting
aquatic
plants
and
algae
1.
Reduction
in
photosynthetic
rate
2.
Reduction
in
abundance
by
dislodgement
and
deposition
II.
Input
of
Organic
debris
A.
Fine
organic
debris
1.
Reduction
of
dissolved
oxygen
2.
Production
of
slime
bacteria
3.
Loss
of
habitat
for
riffle­
dwelling
benthic
invertebrates
and
algae
B.
Large
organic
debris
1.
Debris
jams
a.
Blockage
or
delay
of
juvenile
and
adult
fish
migration
b.
Cover
spawning
and
rearing
areas
2.
Washout
of
debris
jams
a.
Release
of
fine
sediment
b.
Scour
and
destruction
of
benthic
invertebrates
and
salmon
eggs
and
alevins
3.
Contribution
to
channel
and
streambank
instability
by
diversion
of
streamflow
and
washout
