Addressing
Diffuse-Source Pollution of U.S. Coastal Waters
Presentation to the
U.S. Commission on Ocean Policy
January 15, 2001
Changes in loadings to Southern California Bight, 1971-96
Diffuse sources dominate the trace metal inputs
The sources of nitrogen inputs vary among coastal regions
Nutrients causing hypoxia in the Gulf come from far away
COMPS buoy on the Florida
Shelf
Many of the points
made and accompanying figures are included in a report prepared for the Pew Oceans Commission
entitled Marine Pollution in the United States:
Significant Accomplishments, Future Challenges 
.
Point versus Diffuse Sources
The nation’s efforts over the past 30 years under the Clean Water Act (CWA) and other federal statutes have been successful in reducing water pollution resulting from sewage treatment plants, industrial facilities, ships, and the at-sea dumping of sewage sludge and other wastes. Direct discharges into the Southern California Bight, for example, have decreased by 50% in terms of suspended solids and biological oxygen demand and 90% for trace metals.
Although
these toxicants such as DDT and PCB still pose problems due to legacy contamination, their
concentrations in the environment are decreasing in many U.S. coastal
environments.
Pollution from land runoff and the atmosphere went largely
unabated during this period; in some cases it has increased.
Diffuse (or nonpoint) sources now contribute a larger
portion of many pollutants, such as trace metals, than the more thoroughly
regulated direct discharges. Neither the CWA or the Coastal Zone
Management Act (CZMA)
has been very effective in controlling these sources.
New approaches to reduce diffuse source pollution of our
nation’s coastal waters must be a key facet of a new U.S. ocean policy.
Nutrients
Overenrichment of coastal ecosystems by nutrients—nitrogen and phosphorus, but particularly nitrogen—has emerged as the most widespread and measurable effect of pollution on living resources and biodiversity in U.S. coastal waters. This was the subject of an excellent National Research Council report, Clean Coastal Waters: Understanding and Reducing the Effects of Nutrient Pollution . Excessive nutrient loading results in what is referred to as eutrophication, potentially causing serious depletion of dissolved oxygen supplies needed by marine organisms (or hypoxia), loss of seagrass and coral reef habitats, and algal blooms.
Of the 138 estuaries and bays included in a NOAA assessment, 64% had moderate to high levels of eutrophication (map). Fully two-thirds of the surface area of estuaries and bays in the conterminous U.S. suffers one or more symptoms of nutrient overenrichment.
Some large portions of our continental shelf waters are also affected. The largest and most notable of these is the so called “Dead Zone,” an area of seasonal hypoxia on the continental shelf of Louisiana and Texas off the Mississippi River. See the Integrated Assessment of Gulf hypoxia.
Although
coastal environmental and resource managers must struggle with an array of
problems that include habitat loss and modification, the effects of
overfishing, invasive species, and, on the horizon, climate change,
nutrient pollution is seen as the most serious and pervasive problem in
many regions, both at present and into the future. In
fact eutrophication often interacts with fishery harvesting, sometimes
further stressing the ecosystem. 
Major management efforts are under way, not only in the U.S. but
also in Europe and Japan, to reduce nutrient loading in order to
rehabilitate and protect sensitive ecosystems (overview
of these programs). This is a central goal of the Chesapeake Bay
Program, in which
significant reduction of nutrient loading is the central goal.
In 2000 nine states and eight federal agencies agreed to a goal
for reduction of the Gulf of Mexico hypoxic zone that would require
reduction in nitrogen loading by 30%.
Multiple sources from agriculture, stationary and mobile combustion
emissions, waste treatment facilities, and urban runoff must be addressed. These
may originate far beyond the typical domain of ocean and coastal
management (1,000 miles away in the case of the Midwestern Corn Belt and
the Gulf of Mexico). Thus, our national ocean policy in the 21st century
must reach out and influence national agricultural policy, energy policy,
transportation policy and land use policy.
Rapid Development
Land
development, particularly the
proliferation of impervious surfaces on the landscape and associated
increased vehicular transportation, are major factors driving increases in
diffuse source pollutants, both toxicants and nutrients.
Unconstrained growth will undo the gains made in reducing point
source and agricultural diffuse source loadings of pollutants.
In
the urban-suburban core stretching from Baltimore through Washington and
Richmond onto Hampton Roads the rate of land conversion to development has
been nearly three times greater that the population growth.
Efforts are under way in
Maryland and elsewhere in the region to reduce
harmful sprawl development. Many existing federal policies, including transportation funding
and flood insurance, for example, can be adjusted to promote smarter
growth in the coastal zone.
Science and Technology
In stark contrast to the national importance of diffuse-source pollution and the scale of public and private expenditures that are being made and will be made to correct these problems, the nation’s investment in the science needed to guide these efforts is extremely paltry. The U.S. needs a coordinated, strategic research program on diffuse source pollution, and nutrients in particular, that spans air, land and water; focuses on effective solutions; and predicts and observes outcomes. This should be integrated with greatly expanded research and development programs that address coastal ecosystem management from a national perspective. See National Research Council Report Priorities for Coastal Ecosystem Science.
Because of the complex environmental processes influencing eutrophication, the high variability of its symptoms and the practical need to forecast and monitor outcomes, there is compelling value of coastal observation and prediction systems in our efforts to reduce nutrient pollution. This is an important reason for implementing a sustained, integrated ocean observing system for the United States that includes a network of coastal subsystems.
The universities and research institutions of the Southeast, united through the Southeastern University Research Association (SURA), are working to develop the SURA Coastal Ocean Observing Program (SCOOP), a. network of observing systems consistent with the efforts of the Consortium for Ocean Research and Education (CORE) and the national ocean science community, federal agencies and Ocean.US, and the private sector.