13
31
January
2003
EPA
believes
that
the
species
group
approach
is
appropriate
for
the
national
rulemaking
given
the
many
data
limitations
associated
with
our
lack
of
knowledge
of
specific
fish
life
histories,
particularly
the
growth
and
mortality
rates
of
early
life
stages.
However,
EPA
is
not
endorsing
this
approach
for
analyses
to
support
individual
permits
related
to
specific
water
bodies
and
facilities.
At
the
individual
permit
level,
more
detailed
information
regarding
the
life
histories
of
individual
species
is
often
available
and,
when
available,
it
should
be
used.

EPA
evaluated
facility
I&
E
monitoring
data
for
all
individual
fish
species
with
losses
over
1%
of
the
facility
total.
EPA
converted
annual
I&
E
losses
for
each
species
group
into
(
1)
age
1
equivalents,
(
2)
fishery
yield,
and
(
3)
biomass
production
foregone
using
standard
fishery
modeling
techniques
(
Ricker,
1975;
Hilborn
and
Walters,
1992;
Quinn
and
Deriso,

1999).
Details
of
these
methods
are
provided
in
Chapter
A5
of
Part
A
of
the
§
316(
b)
Phase
II
Case
Study
Document
and
the
preamble
to
the
NODA.
Section
A5­
4
of
Chapter
A5
discusses
data
uncertainties.
For
all
analyses,
EPA
assumed
100%
entrainment
mortality
based
on
the
analysis
of
entrainment
survival
studies
presented
in
Chapter
A7
of
Part
A
of
the
§
316(
b)
Phase
II
Case
Study
Document
To
obtain
regional
I&
E
estimates,
EPA
extrapolated
losses
from
facilities
with
I&
E
data
to
facilities
without
data.
These
results
were
then
summed
to
obtain
a
regional
total.
Average
annual
results
for
facilities
with
impingement
and
entrainment
I&
E
data
were
averaged
and
extrapolated
on
the
basis
of
operational
flow,
in
millions
of
gallons
per
day
(
MGD),
to
facilities
without
data.
The
extrapolation
method
used,
by
region,
is:

Total
losses
at
case
study
facilities
*
Flow
at
case
study
facilities
/
Total
flow
in
the
region
