Page
1
of
1
Memorandum
From:
Tom
Born
USEPA/
OW/
OST
ph:
(
202)
566
1001
born.
tom@
epa.
gov
To:
Public
Record
for
the
Effluent
Guidelines
Program
Plan
for
2004/
2005
DCN
00777,
Section
2.1.4
EPA
Docket
Number
OW­
2003­
0074
(
www.
epa.
gov/
edockets/)

Date:
March
9,
2004
Re:
Typical
Pollutant
Concentration
(
TPC)
Documentation
for
the
303(
d)
Impaired
Waters
Analysis
The
purpose
of
this
memorandum
is
to
place
into
the
304(
m)
docket
the
Typical
Pollutant
Concentration
(
TPC)
Documentation
for
the
303(
d)
Impaired
Waters
Analysis.
The
TPC
documents
were
prepared
by
the
Office
of
Enforcement
and
Compliance
Assurance
in
the
year
2000.

TPCs
­
average
pollutant
concentrations
by
SIC
­
were
used
to
assign
minor
facilities
to
impaired
waters,
because
minors
have
little
or
no
permit
limit
information
in
PCS.
Permit
limit
information
was
used,
primarily
for
major
facilities,
to
match
facility
pollutant
discharges
to
waterbody
impairments.
Note
that
over
counting
may
occur
when
matches
are
based
on
TPCs
­
some
facilities
might
not
actually
discharge
some
or
all
of
the
TPC
assigned
pollutants.
