SORU: aşağıdaki parçaya göre cevaplayınız
We learn from the passage that one gratifying sign that the Chesapeake Bay is no longer seriously polluted is the fact that ---- .
Like so many American waterways, the Chesapeake
Bay, an enormous, semi-saline body of water that is
treasured for its aquatic life, became badly polluted
during the 20th century. But it has regained much of
its biological vitality since the early 1970s, thanks to
concerted ecological stewardship. In this effort, the
Conowingo dam has provided valuable assistance.
Environmentalists are not often fond of dams, which
have a habit of trapping migratory fish and
disrupting sensitive water ecosystems - not to
mention looking ugly. But the Conowingo dam on
the Susquehanna river in eastern Maryland is an
exception. Since its construction in 1928, the
Conowingo dam has not only generated electricity
but also trapped vast amounts of sediment behind
its imposing walls. This was not a function the
builders had planned for, but in recent years its
value has become clear. The water flowing past the
Conowingo dam is much cleaner than it would
otherwise be. Even America's onceendangered
national symbol, the bald eagle, can be seen
perching near the dam, waiting to swoop down and
seize a meal of fish by its talons.