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Late August 2020 Hypoxia Report

Oxygen Conditions Better than Average

Map of Chesapeake Bay Dissolved Oxygen results for late August 2020Maryland Department of Natural Resources monitoring data show that dissolved oxygen conditions in the Maryland portion of the Chesapeake Bay mainstem were better than average in late August 2020. The hypoxic water volume — areas with less than 2 mg/l oxygen — was 0.79 cubic miles compared to a historical late August average (1985-2019) of 1 cubic mile. Oxygen conditions continued to be better than average in 2020, with only late July results exceeding the long-term average.

Late August conditions ranked 12th best out of the 36-year monitoring record for the period. No hypoxia was observed in Virginia Chesapeake Bay mainstem waters. No anoxic zones — areas with less than 0.2 mg/l oxygen — were observed in the Maryland or Virginia mainstem.

Graph of percentage of hypoxic water volume in Chesapeake Bay, late August 2020Maryland’s water quality data can be further explored with a variety of online tools at the Department’s Eyes on the Bay website.

Improved oxygen conditions thus far in 2020 are in agreement with forecast results. 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 hypoxic conditions based on slightly less than average water and nitrogen flows into the bay from January to May 2020.

Graph of comparative historic volumes of dissolved oxygen in the Chesapeake BayCrabs, fish, oysters, and other creatures in the Chesapeake Bay require oxygen to survive. Scientists and natural resource managers study the volume and duration of bay hypoxia to determine possible impacts to bay life. Each year from June through September, the Maryland Department of Natural Resources computes these volumes from data collected by Maryland and Virginia monitoring teams during twice-monthly monitoring cruises. Data collection is funded by these states and the Environmental Protection Agency’s Chesapeake Bay Program. Bay hypoxia monitoring and reporting will continue through the summer.