Appendix 1
Trading Program
The Tar-Pamlico
Background
Tar-Pamlico
Trading Program
..
Over the
20 years, a great deal of research has occurred in the Pamlico
River Estuary related to the eutrophication of the system, and more specifically, to
the culturally induced acceleration of the eutrophication process. Researchers
have concluded that nitrogen is the limitirig factor for plant growth in the estuarine
portion of the Tar-Pamlico basin (NCDEM, 1987). Ongoing research is focusing
on the estuarine system's response to nutrient inputs and to the magnitude and
inputs from various sources. This research, along with growing
timing of
public awareness, has led to the adoption of management strategies to better
control eutrophication.
Nutrient budgets (estimates of the magnitude of point and
source
nutrient loading) have been calculated for the Tar-Pamlico basin to aid in the
development of strategies. A nutrient source budget was first prepared in 1986
two
by the North Carolina Division of Environmental Management
major events have subsequently occurred. First, the North Carolina General
Assembly enacted a ban on the sale of phosphate detergents. Then, a new
NPDES permit was issued to Texasgulf Industries, Inc., a phosphate mining
operation whose total phosphorus loads were estimated to account for about 50
percent of the phosphorus inputs for the entire basin. After revising the budget to
account for changes due to the phosphate ban and the Texasgulf permit, the
North Carolina Division of Environmental Management (NCDEM) estimated that
approximately 66 percent of the total phosphorus in the basin could be attributed
sources, approximately 25 percent to point source dischargers other
to
than Texasgulf, and the remaining 9 percent to Texasgulf Industries, inc.
three percent of the total nitrogen in the basin could be attributed to
sources, primarily agricultural runoff and, to a lesser extent, urban runoff and
atmospheric deposition (NCDEM, 1989).
The development of a
strategy
the Tar-Pamlico was
complicated because the
and the new Texasgulf permit were
enacted after the nutrient budgets had been calculated. NCDEM was uncertain
about how much these changes would improve water quality; however, because
of continuing demands on the system's assimilative capacity, they could not
afford to wait until all the necessary information had been obtained through
monitoring and research. Consequently, NCDEM proposed an interim strategy
that required mandatory limits on nitrogen and phosphorus for new and
expanding dischargers in the basin. The aim of the strategy was to halt point
source increases while studies were being conducted. The NSW strategy
specified effluent concentration limits of 2
for total phosphorus throughout
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