2.
Response
to
Comments
2.9
Individual
Responses
to
Comments
from
Organizations
or
parking
lots
and
can
carry
with
it
pollutants
such
as:
oil,
pesticides,
herbicides,
sediment,
trash,
bacteria
and
metals.
The
runoff
can
then
drain
directly
into
a
local
stream,
lake,
or
bay.
Often,
the
runoff
drains
into
storm
drains,
which
eventually
drain
untreated
into
a
local
water
body
(SWRCB).
Additionally,
municipal
or
urban
areas
commonly
include
large
impervious
surfaces
that
contribute
to
an
increase
in
runoff
flow,
velocity,
and
volume.
As
a
result,
streams
are
hydrologically
impacted
through
streambed
and
channel
scouring,
in-stream
sedimentation
and
loss
of
aquatic
and
riparian
habitat.
In
addition
to
hydrological
impacts,
large
impervious
surfaces
contribute
to
greater
pollutant
loading,
resulting
in
turbid
water,
nutrient
enrichment,
bacterial
contamination,
and
increased
temperature
and
trash
(SWRCB).
MS4
permits
were
issued
in
two
phases.
Under
Phase
I,
which
started
in
1990,
Regional
Water
Quality
Control
Boards
statewide
adopted
National
Pollutant
Discharge
Elimination
System
General
Permit
(NPDES)
storm
water
permits
for
medium
(serving
between
100,000
and
250,000
people)
and
large
(serving
250,000
people)
municipalities.
Most
of
these
permits
are
issued
to
a
group
of
co-permittees
encompassing
an
entire
metropolitan
area.
These
permits
are
reissued
as
the
permits
expire.
The
Phase
I
MS4
permits
require
the
discharger
to
develop
and
implement
a
Storm
Water
Management
Plan/Program
with
the
goal
of
reducing
the
discharge
of
pollutants
to
the
maximum
extent
practicable
(MEP).
MEP
is
the
performance
standard
specified
in
Section
402(p)
of
the
Clean
Water
Act.
The
management
programs
specify
what
best
management
practices
(BMPs)
will
be
used
to
address
certain
program
areas.
The
program
areas
include
public
education
and
outreach;
illicit
discharge
detection
and
elimination;
construction
and
post-construction;
and
good
housekeeping
for
municipal
operations.
In
general,
medium
and
large
municipalities
are
required
to
conduct
monitoring
(SWRCB).
On
April
30,
2003
as
part
of
Phase
II,
the
State
Water
Resources
Control
Board
issued
a
General
Permit
for
the
Discharge
of
Storm
Water
from
Small
MS4s
(WQ
Order
No.
2003-0005-DWQ)
to
provide
permit
coverage
for
smaller
municipalities
(population
less
than
100,000),
including
non-traditional
Small
MS4s,
which
are
facilities
such
as
military
bases,
public
campuses,
prison
and
hospital
complexes.
The
Phase
II
Small
MS4
General
Permit
covers
Phase
II
Permittees
statewide.
On
February
5,
2013
the
Phase
II
Small
MS4
General
Permit
was
adopted
and
became
effective
on
July
1,
2013
(SWRCB).
The
concept
of
keeping
stormwater
onsite
and
allowing
it
to
percolate
into
the
underlying
media
is
generally
regarded
as
a
best
management
practice,
and
is
regularly
employed
to
comply
with
the
new
stormwater
regulations.
Various
mechanisms
are
available,
including
but
not
limited
to,
infiltration
ponds,
bioswales,
tree
wells,
and
stormwater
chambers.
However,
such
percolation
Brisbane
Baylands
Final
EIR
2.9.1-89
May
2015