National
Water
Quality
Assessment
Program
January
21,
2003
Purpose:
:
Since
1991,
USGS
scientists
with
the
NAWQA
program
have
been
collecting
and
analyzing
data
and
information
in
more
than
50
major
river
basins
and
aquifers
across
the
Nation.
The
goal
is
to
develop
long­
term
consistent
and
comparable
information
on
streams,
ground
water,
and
aquatic
ecosystems
to
support
sound
management
and
policy
decisions.
The
NAWQA
program
is
designed
to
answer
these
questions:

1.
What
is
the
condition
of
our
Nation's
streams
and
ground
water?
2.
How
are
these
conditions
changing
over
time?
3.
How
do
natural
features
and
human
activities
affect
these
conditions?

Chemicals:
The
assessment
includes
500
chemical
constituents.

Sample
Locations:
NAWQA
study
units
are
major
river
basins
and
aquifers
across
the
Nation.
A
study
unit
boundary
frequently
crosses
state
boundaries
and
usually
encompasses
more
than
10,000
square
kilometers
(
about
3,900
square
miles).
Study
units
are
the
building
blocks
of
NAWQA
and
form
the
basis
for
national
synthesis
assessments.
How
were
study
units
selected?
Geographic
areas
were
selected
to
represent
a
variety
of
important
hydrologic
and
ecological
resources;
critical
sources
of
contaminants,
including
agricultural,
urban,
and
natural
sources;
and
a
high
percentage
of
population
served
by
municipal
water
supply
and
irrigated
agriculture.
What
is
the
scope
of
study­
unit
investigations?
Studies
are
long­
term
and
cyclical.
One­
third
of
all
study
units
are
intensively
investigated
at
any
given
time
for
3­
4
years,
followed
by
low­
intensity
monitoring.
Trends
are
assessed
about
every
10
years.
1991
­
2001
(
51
study
units)
The
first
cycle
of
intensive
investigations
began
with
20
study
units
in
fiscal
year
1991;
investigations
of
additional
study
units
began
in
1994,
1997,
and
1999.
2001
­
2012
(
42
study
units)
The
second
cycle
of
intensive
investigations
began
in
2001
in
14
study
units
that
were
intensively
assessed
during
the
first
cycle
from
1991­
95.
Investigations
will
begin
in
14
more
study
units
in
2004
and
in
another
14
in
2007.

Sample
Design:
The
U.
S.
Geological
Survey
(
USGS)
began
its
NAWQA
(
National
Water
Quality
Assessment)
program
in
1991,
systematically
collecting
chemical,
biological,
and
physical
water
quality
data
from
study
units
(
basins)
across
the
nation.
The
data
warehouse
currently
contains
and
links
the
following
data
up
through
9/
30/
2001:
Chemical
concentrations
in
water,
bed
sediment,
and
aquatic
organism
tissues
for
about
500
chemical
constituents
Site,
basin,
well
and
network
characteristics
with
many
descriptive
variables
Daily
stream
flow
information
for
fixed
sampling
sites
Ground
water
levels
for
sampled
wells
4,100
surface
water
sites
and
6,500
wells
46,000
nutrient
samples
and
31,000
pesticide
samples
as
well
as
9,600
VOC
samples
3,200
samples
of
bed
sediment
and
aquatic
organism
tissues
.

Time
period
Covered:
The
program
began
in
1991
and
is
envisioned
to
continue
in
10
blocks
until
at
least
2012.

Evaluation
Method:
The
National
Synthesis
Team
will
publish
reports
on
national
water
quality
using
information
obtained
from
the
study
units.
The
Nutrients
and
Pesticides
report
is
available
now.
Reports
for
voc's,
aquatic
ecology
and
trace
elements
are
planned.
There
are
summary
reports
available
for
the
individual
study
units
as
well.

Results:
There
is
a
NAWQA
data
warehouse
available
online.
It
allows
the
user
to
search
by
location
or
chemical
of
interest.

Short
Term
Followup:
Look
at
the
individual
and
national
summary
reports
for
usefulness.

Long
Term
Followup:
Can
the
data
warehouse
be
cross
referenced
to
other
databases?
