ANNAPOLIS – Slow-moving, nutrient-rich groundwater may frustrate efforts to meet a 2010 deadline for cleaning up the Chesapeake Bay, said the U.S. Geological Survey in a recent study.
Maryland and other Chesapeake Bay Program partners have already implemented measures to fulfill bay nutrient- and sediment-reduction commitments by the deadline, said program Assistant Director Mike Burke.
But groundwater takes about 10 years to flow into streams and into the bay, delaying visible signs of water quality improvement, said the survey.
The study is a “two-edged sword,” Burke said. “We know we have some benefits we have not yet seen (but also), it serves as a real spur to act fast.”
The Environmental Protection Agency named the bay an “impaired water body,” mainly due to the crippling effects of an overabundance of nitrogen and phosphorous on the estuary’s fragile ecosystem.
The nutrients encourage algal blooms, which deplete the bay of oxygen, resulting in the death of underwater grasses, the presence of toxic bacteria and damaged fisheries.
Farm runoff is the most obvious source of nutrient pollution, however, groundwater contributes about 48 percent of nitrogen in streams, the report said, making it a crucial conduit for nutrient transport into the estuary.
Nitrogen enters groundwater from rainfall, snowmelt, and dissolved fertilizers that percolate down through the soil into underground basins.
In the mid-1980s, the Chesapeake Bay Program began efforts to reduce bay nutrients, but improvement has been slow.
Under a 2000 agreement, Maryland, Virginia, and other bay states committed to voluntary cleanup targets including cutting nitrogen and phosphorous loads by 40 percent from 304 million pounds to 188 million pounds per year.
The multi-agency partnership, including the District of Columbia, has already implemented several measures, Burke said, including applying nutrient management practices to about 3 million acres of agricultural land and to 100 sewage treatment facilities.
In this legislative session alone, Maryland lawmakers introduced bills to improve sewage treatment, establish funds for cleaning the bay and streamline mandatory farm nutrient-management-plan submissions, hoping to raise farmer compliance from 75 to 100 percent.
States also have to submit plans for achieving nutrient-reduction goals in the more than 30 different subwatersheds and tributaries leading into the bay by April of this year, according to the program.
The study means states “will have to implement the plans as soon as possible to offset the influence of groundwater residence times,” said USGS Chesapeake Coordinator Scott Phillips.
Groundwater spends from 1 to 50 or more years in shallow aquifers below the Chesapeake Bay watershed, USGS said, while runoff and soil water range are only hours or months old, respectively.
This and other data in the study will be extremely helpful to the program’s efforts, said Burke.
The study, which was released Feb. 18, would also be helpful to constructing water quality management plans in other areas, said Phillips.
“The bay is a good pilot for what happens in other parts of the country,” he said. “(This study) should be able to be applied to coastal systems nationwide.”