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Nitrogen Limits for Treatment Plants Recommended to Restore Chesapeake Bay
Harm caused by excessive nutrients in the Chesapeake Bay could be reversed if
water pollution permits for sewage treatment plants contained nitrogen limits,
an environmental group said Oct. 29.
The Chesapeake Bay Foundation said that even though nitrogen is known to be a
significant cause of impairment for the bay, most sewage treatment plants do not
utilize technologies to reduce discharges of the nutrient and most permits do
not require it.
"We say they do have the authority to put nitrogen limits in permits," Charles
Fox, vice president of the organization, said.
CBF issued a report, Sewage Treatment Plants: The Chesapeake Bay Watershed's
Second Largest Source of Nitrogen Pollution, analyzing the effects of nitrogen
from wastewater treatment facilities. Agriculture and air deposition also are
leading sources of nitrogen in the bay, the group said.
Blue Plains Wastewater Treatment Plant in Washington, D.C., is a facility that
does use advanced treatment technologies to curb nitrogen discharges. The
largest advanced sewage treatment plant in the world, Blue Plains treats about
340 million gallons per day of wastewater, including nitrogen removal. In the
past eight years, nitrogen discharges dropped from about 15 milligrams per liter
to 6 mg/l, but the Chesapeake Bay Foundation would like to see the plant reduce
discharges to about 3 mg/l.
The foundation looked at 265 of about 300 major treatment plants in Maryland,
Pennsylvania, Virginia, and Washington, D.C., and found that only 10 currently
employ state-of-the-art technology, such as the biological nutrient removal
system used at Blue Plains. Altogether, the plants release about 52 million
pounds of nitrogen into the bay annually, CBF said.
The Chesapeake Bay Executive Council, composed of the governors of Maryland,
Pennsylvania, and Virginia, the mayor of the District of Columbia, and the
administrator of the Environmental Protection Agency, approved a plan known as
Chesapeake 2000 that set a goal of restoring the bay by 2010. CBF said that
milestone cannot be reached absent a renewed compact that would establish
stricter regulatory controls, more incentives, and more money to reverse
declining water quality in the bay (163 DEN A-6, 08/22/03 ).
"Progress is way too slow to meet the commitments of the Chesapeake 2000," John
Page Williams, senior naturalist with CBF, said. "There are some indications of
progress, but not enough to keep up with growth in the region."
Fox said one manifestation of the excess nitrogen is a "dead zone" in the middle
of the bay during the summer months devoid of much aquatic life because of
little or no oxygen. Algae flourishes in waters with excess nutrients, but when
they die, they decompose using up oxygen.
The Clean Water Act provides the authority to incorporate nitrogen limits into
National Pollutant Discharge Elimination System permits, Fox said.
In response to a query from Virginia officials, the federal Environmental
Protection Agency sent a letter Sept. 30 affirming that they not only are
authorized to set limits for nitrogen, but have "the prime responsibility to
promulgate and interpret water quality standards which set the desired uses of
waterways and specific water quality criteria to protect them."
The letter from G. Tracy Mehan, EPA assistant administrator for water, said
Virginia's water quality standards include "broad and specific authorities ...
to control nitrogen."
Wastewater treatment plant officials do not disagree about the water quality
problems facing the bay, but said too much focus is placed on nutrient control
from publicly owned treatment works.
Other factors contributing to the problem are excessive sediment loads,
especially during rainy years, and the decimation of the oyster population in
the bay. Agricultural and urban stormwater runoff also add nutrients to the bay.
Some wastewater officials have said nitrogen and phosphorus levels are not good
indicators of progress in restoring the ecosystem. Rather, regulators should
focus on factors such as dissolved oxygen levels and water clarity.
Dissolved oxygen levels in the deepest channel of the bay have historically been
low and can never be brought to the higher levels in the shallower waters,
Clifton Bell, a consulting engineer in Newport News, Va., said at an Association
of Metropolitan Sewerage Agencies conference in July (140 DEN A-6, 7/22/03).
"The waters John Smith sailed over were pretty low in oxygen," he said.