The Chesapeake Bay’s Shrinking ‘Dead Zones’

As nutrient pollution into the bay decreases, fewer algae blooms mean there is more dissolved oxygen available in the water available for fish and other marine animals that require oxygen to survive.

Dissolved Oxygen Levels (Late August)

1 mg/L or less: Dead zone
1-3 mg/L: Sub-optimal
More than 3 mg/L: Acceptable

Map of dissolved oxygen levels in the Chesapeake Bay in 1988

Map of dissolved oxygen levels in the Chesapeake Bay in 2015

Note: Dissolved oxygen is measured in milligrams per liter.