1e ThDlly New., FrIOy, .April 10, Environment
Unpaved roads increase sediment pollution
This second column on St. development of tourism. ln the iste
John's threatened environment 1950.s there was only oo bulldoes-
focuses on whether roads have er. two jeepa and one truck on the
impacted tbe marne environment. Island. Boats were the primary
We leamod las week that his- transport.
torical records showed little evi- In 156. two-thrd of StL John's
deoce of impact oa the marine life land became the Virgin Islands
of St. John by the activities of National Park. Undoubtedly, the
Indiana. BEropeans sad colonies- park helped epark te development
tion and slave. of orim on te lad.
The rejuvenaton of the St John By the 1960s, the lomist laods-
economy began with the slow try on St John picked up Iebetan-
daiy. bringing In millions of dol.
Ilas and one million visitors each
But the growing demand for
recreational use of St. John created
a need for short-term aooommods-
tions, home development, exten-
dse roads network and the overall
InItucure to support the indus-
Thus, scientists believe the
Isod-use changes of St. John are
the primary cause for the acoelera-
Lon of sedimentation.
Although goats, pigs and don-
keys have impacted the natural
vegetation those ipas are difl.-
cult to calculate due to the lack of
data on undisturbed and grazed
aites. Please do not get me wrong.
animals do impact the environ.
ment, bat bow much is another
Nonetheless, urban develop-
ment and the network of roads are
probably the primary source of
Scientists Donald M. Anderson
and Lee IL. MacDonald Investigat-
d paved and unpeved roads on St.
lobs. By taking cross-sectlonal
measurements of eroded road sur-
faces, they found that unpaved
roads "are the largest sediment
source on St. John," according to
Anderan and MacDonald esti-
mated road surface eroilon In two
St. John catchmenta with very dif-
ferent road densities but similar
land cover, topography and soils.
They found thai unpaved roads
increased ediment production by
anywhere from one-and-a-half to
eight times the normal rate,
depending on how densely roaded
the area was.
There are many attractions at
the park on St. John. But the pri-
mary attractions are the white
sandy beaches. coral reeft and the
clear nersbore waten surrounding
the park. Coral reefs e extremely
sensitive organisms to sedimentL
Many residents have reported
that after rain, the bays oCLt, John
are brown as soil washtedkdowu
from the hillsides of the island.
About 82 percent of St. John is
covered by dry evergreen wood-
land, dry evergreen $crub and
thicker, moist evergreen forest,
secondary growth forest and other
ecosystems such as mangrove,
theory and cactus. Only about 2 per-
cent of the land ais pasture. There
are virtually no agriculture actlvl-
The largest source of lasd Us-
turbance is urban development,
private home construction and the
network of roads.
According to studies. sediment
discharge from individual homes'
construction appears to be mini-
mized due to limited land distur-
bance and the widespread use of
soil control methods, such s vege-
tative filters and lill fences to
Studies showed that aecumuls-
tionS of fine sediment were evi-
dent where roads dralind from
hillside slopes downstream into
mangrove marshes and coastal
"These observations, together
with our estimate of sediment
yields from undisturbed waters led
us to posit the erosion from
unpaved roads in the largest source
of sediment on St. John." MacDon-
.., Unpaved roads are Just one of
tWi many problems park officials
hpve to address. Education and
cooperation with the public are the
keys in solving many of the prob-
Ietms that threatened the park envi-
roament on St.'John.
Fees are one way to address
these problems. It takes money to
run a quality park environment:
aTis article reflects the rV w of
Olasme Davif a S. Croti ecoltogs
activist and wrter who has a mas,-
ser qfcleace daele is range man-
tityee endjfrestry ecolee.