Impact of highway runoff on stream quality in the Sevenmile Creek Basin near Efland, North Carolina
U.S. Geological Survey Southeast Region Water Quality Symposium,
Jacksonville, Florida, 1984
By Douglas A. Harned
Abstract
An evaluation of water quality of the streams receiving storm-water
runoff from a segment of interstate highway showed elevated levels
of many constituents compared to nearby undeveloped basins.
Additional data collected from an elaborate network of dry and
wet precipitation collectors, lysimeter samples, soil surveys,
wind measurements and road sweepings have helped to define the
general sources and migration of contaminants near the highway.
The study area basins had a combined area of 17.5 square miles,
and drained a 4.8 mile-long segment of Interstate highway 85
with an average traffic flow of 25,000 vehicles per day.
During storm runoff, streamflow in streams near the highway rose
and fell more rapidly than in streams in the undeveloped basins.
Streamflow correlated well with the transportation land-use
category.
The highway stations showed the highest specific conductance,
calcium, sodium, chloride, dissolved solids concentrations,
and alkalinity, primarily due to road salting. Storm water-quality
response at the beginning of a storm shows a rapid peaking of specific
conductance and concentration of dissolved and total nitrogen.
The highway had little effect on suspended sediment, water temperature,
dissolved oxygen, and pH. Storm flow brought a depression in pH at
all stations as rainfall with pH values less than 3.7 pH units was
drained off by the streams.
High metals concentrations were found in the soils near the road and
the shallow ground water draining through the soils. Chromium, copper,
nickel, and zinc concentrations in the streams near the road were
generally above recommended levels for the protection of aquatic life,
and lead and cadmium concentrations frequently exceeded levels
recommended for drinking water. High concentrations of metals
in precipitation, including cadmium, chromium, iron, lead, nickel,
and zinc, were measured in samples taken near the road and about a
kilometer away.
The highway clearly serves as a source of contamination to surrounding
areas. Constituent loads in dustfall and constituent concentrations in
soils decrease exponentially with distance from the road, with
the highest concentrations on the downwind side. Material loading
from precipitation is greater for dry periods than wet periods. Loads
of saltated particles are higher than other particle deposition.
Saltation loads peaked during the winter months, due probably to
road deicing and sanding which also supplies an estimated two thirds
of available solids with the rest coming primarily from deposition of
particles from vehicles.
Citation:
Harned, D.A., 1984, Impact of highway runoff on stream quality in the Sevenmile Creek Basin near Efland, North Carolina [abs]: U.S. Geological Survey Southeast Region Water Quality Symposium, Jacksonville Florida.
For more information, contact |
To order printed copies, contact |
North Carolina Water Science Center
U.S. Geological Survey
3916 Sunset Ridge Road
Raleigh, North Carolina 27607
(919) 571-4000
E-mail
|
North Carolina Water Science Center
U.S. Geological Survey
3916 Sunset Ridge Road
Raleigh, North Carolina 27607
(919) 571-4037
E-mail
|
U.S. Geological Survey
Information Services
Box 25286, Federal Center
Denver, CO 80225
1-888-ASK USGS
|
|