Document Type



Virginia Institute of Marine Science

Publication Date



The “Dead Zone” of the Chesapeake Bay refers to a volume of bottom water that is characterized by dissolved oxygen concentrations less than 2 mg/L, which is too low for aquatic organisms such as fish and blue crabs to thrive.The Chesapeake Bay experiences such “hypoxic”conditions every year, with the severity varying from year to year, depending on nutrient and freshwater inputs, wind, and temperature. Multiple metrics are used to relate the severity of hypoxia between different years:

  • Hypoxic Duration (days): The number of days in a given year between the first and last day of hypoxic conditions exceeding 2 km3in volume
  • Total Annual Hypoxic Volume (km3days): The total amount of hypoxia in the Bay for a given year, calculated by summing the hypoxic volume on each day
  • Maximum Daily Hypoxic Volume (km3): The greatest volume of Chesapeake Bay water experiencing hypoxic conditions on any day of the year


Chesapeake bay, water quality, hypoxia