Hypoxia Report Card

Compare the annual severity of Chesapeake Bay hypoxia

During Fall 2017, the Virginia Institute of Marine Science joined with Anchor QEA to release their first retrospective seasonal analysis of the severity of hypoxia in Chesapeake Bay. The Annual Chesapeake Bay Hypoxia Report Card summarizes dissolved oxygen concentrations in the Bay as estimated by the team's 3-D, real-time hypoxia forecast model. The modeling team also generated the same dissolved oxygen statistics for 3 previous years for comparative purposes. Partial funding for this project comes from NOAA, in collaboration with researchers at the University of Maryland Center for Environmental Science and the Woods Hole Oceanographic Institution.

Download a printable pdf copy of the report card here.

Report Card Metrics

The forecast and report card use multiple metrics to quantify and compare hypoxic severity:

  • Hypoxic Volume: volume of water (km3) experiencing hypoxic conditions (<2mg/L) at any one time
  • Average Summer Hypoxic Volume from June through September
  • Cumulative Hypoxic Volume: total amount of hypoxia in the Bay for a given year, calculated by summing the hypoxic volume in km3 on each day
  • Duration of Hypoxia: number of days the Bay experiences hypoxic conditions exceeding 2 km3 in volume
Synopsis for 2017

Springtime inflows from the Susquehanna River were high in 2017, resulting in the prediction that 2017 would have a larger than average summer hypoxic volume. However, summer winds and temperatures also play a large role in determining the amount of hypoxia in a given year. During 2017, relatively strong winds in the first half of May delayed the onset of hypoxia relative to 2014 and 2016. However, hypoxia increased very rapidly in early June, and peaked at a higher value in mid-June than in earlier years. Particularly windy periods in late June, July, and August resulted in decreases in hypoxia from the earlier peaks in each of those months.

Summed Annual Estimates

Here we describe the severity of hypoxia as estimated by the forecast model. We define hypoxia as dissolved oxygen concentrations less than 2 mg/L. Duration refers to the number of days the Bay experiences hypoxic conditions exceeding 2 cubic kilometers (km3) in volume.

Time Series Estimates

Strong winds in early May 2017 delayed the onset of hypoxia relative to 2014 and 2016. Windy periods in late June, July, and August decreased hypoxia from earlier peaks in each month.