Mr.
Mayhew,

As
a
follow
up
to
our
call
yesterday,
here
are
answers
to
the
two
questions
you
raised
about
the
Ohio
River
316(
b)
case
study:

Q1:
How
did
EPA
convert
daily
mortality
rates
to
mortalities
by
stage?

Answer:
To
obtain
mortalities
by
stage,
EPA
multipled
the
daily
mortality
rate
by
the
stage
duration
(
in
days).
The
stage
durations
used
for
these
calculations
are
presented
in
the
EXCEL
workbooks
of
input
data
for
the
Ohio
facilities
included
in
the
case
study,
available
in
the
docket
on
the
CD­
ROM
at
DCN
#
4­
1305.

Q2:
How
did
EPA
use
life
history
data
presented
in
the
1999
Salem
Permit
Renewal
Application
given
that
the
species
impinged
and
entrained
at
Salem
are
primarily
estuarine
species,
whereas
Ohio
species
are
all
freshwater
species:

Answer:
EPA
used
the
Salem
data
in
a
few
limited
cases
for
which
information
was
unavailable
for
the
Ohio
River
species.
As
indicated
in
Appendix
C1
to
the
Ohio
case
study
report,
this
included
estimated
size­
at­
age
for
alewife
and
striped
bass
and
egg
mortality
for
yellow
perch.

I
hope
this
information
is
helpful.
Please
don't
hesitate
to
call
if
you
have
additional
questions.

Liz
Strange
Elizabeth
M.
Strange,
Ph.
D.
Manager
Stratus
Consulting
Inc.
P.
O.
Box
4059
Boulder,
CO
80306­
4059
E­
mail:
estrange@
stratusconsulting.
com
Phone:
303­
381­
8000
FAX:
303­
381­
8200
