In mid-June, the EPA Chesapeake Bay Program, United States Geological Survey, University of Maryland Center for Environmental Science and University of Michigan scientists released their prediction for slightly smaller than average 2020 Dead Zone. This prediction was based on slightly less than average water and nitrogen flows into the bay from January – May 2020.
At various times each summer the Maryland Department of Natural Resources measures the dissolved oxygen in the Maryland portion of the Chesapeake Bay main stem and the size of the Dead Zone. While the Virginia Institute of Marine Science (VIMS), Anchor QEA and collaborators at UMCES, operate a real-time three-dimensional hypoxia forecast model using input of that predicts daily dissolved oxygen concentrations throughout the Bay (www.vims.edu/hypoxia) using the National Weather Service wind monitoring data.
The peak of oxygen depletion typically occurs in July or August. Water temperatures are highest during these months and the days are longest accelerating the growth of phytoplankton that ultimately consumes all the dissolved oxygen. The dead zone is typically gone by late fall. Cooler air temperatures at that time of year chill the surface waters, while the deeper water remains warm and allows more mixing of the layers during storms. Cooler water also will hold more oxygen. The size and shape of the dead zone is variable from month to month during the summer.
In the fall of each year, the Virginia Institute of Marine Science and Anchor QEA release a retrospective seasonal analysis of the severity of hypoxia in the 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. We should see that report in two to three months. The modeling team also generates the same dissolved oxygen statistics for previous years for comparative purposes you can look at the past few years below.