RAIN
GARDENS
A RAIN GARDEN MANUAL FOR SOUTH CAROLINA
As development increases, so
does the area of impervious
surface. Impervious surfaces
include roadways, rooftops,
parking lots and sidewalks.
Without planning and appro-
priate management, water that
runs over these surfaces picks
up pollutants along the way
and carries them directly to
our lakes, rivers and estuar-
ies. These pollutants include
bacteria, nutrients, litter, sedi-
ment, oils and metals. Water
that heats up on parking lots
and roadways also can lead
to warmer than normal water
entering nearby waterways.
This runoff, called “stormwa-
ter,” is generated by precipita-
tion, snow melt and irrigation
water that runs off the land.
Stormwater is the greatest
threat to our nation’s surface
waters.
As well as creating hard sur-
faces where pollutants can be
washed into waterways, imper-
vious surfaces also prevent the
natural infiltration process that
occurs in forests, fields and open
areas. Instead of adding to the
groundwater supply, stormwa-
ter flushes the landscape, often
leading to increased flooding,
erosion, sedimentation and
damage to wetlands, ecosys-
tems and waterways.
Rain gardens have become a
popular and attractive method
for property owners to decrease
the impact of their impervious
surfaces. Rain gardens are land-
scaped depressions that receive
stormwater runoff and allow
the runoff to slowly infiltrate
to the groundwater table. As
well as intercepting stormwater
runoff that could have added
to flooding problems, the rain
garden allows nature to play
a role, removing some of the
pollutants that would have oth-
erwise affected water quality.
During infiltration, plants use
excess nutrients for growth,
sediment is trapped in the gar-
den and biological processes
remove pathogens. Dissolved
metals and nutrients bind or
adsorb to soil particles, and are
removed temporarily out of the
system. Rain gardens, like any
garden, also become habitat
for bees, birds and butterflies.
GREEN SOLUTI