The Chesapeake Bay is the largest estuary in North America and
the third largest in the world. Water quality problems are
particularly challenging because it is relatively shallow
compared with the land mass—64,000 square miles—which drains
into it. EPA has called it a “world-class ecological treasure
that is home to several thousand species of plants and animals,”
including migratory birds. Its production of crabs, oysters and
other seafood, plus recreational uses and shipping, “make the
Chesapeake Bay a multi-billion dollar economic driver for the
mid-Atlantic.” Over a century of pollution from heavy
industrial, commercial, agricultural and other uses has resulted
in serious degradation. The principal pollutants are nitrogen,
phosphorus and sediment, which have prevented attainment of
water quality standards for dissolved oxygen, clarity/underwater
grasses and chlorophyll-a (a measure of algae levels). In the
summer large “dead zones” spread out across the Bay where fish
cannot live because the oxygen is de