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Chesapeake Bay Hypoxia Report – Late Summer 2024

Dissolved oxygen conditions continue to be better than average in August

Comparative graph of hypoxic volume in the Chesapeake Bay, by monthData collected by the Maryland Department of Natural Resources and Old Dominion University show a smaller-than-average volume of hypoxia—waters with less than 2 mg/l oxygen—in the Chesapeake Bay mainstem of Maryland and Virginia in early and late August.

Summary results from Maryland and Virginia combined Chesapeake Bay mainstream water quality monitoring cruises are as follows.

Cruise 2024 Hypoxic Volume Historical Average Hypoxic Volume (1985-2023)

*2024 Rank / 

Number of years measured

 Graphic
May

0.42 cubic miles

0.18 cubic miles

35th / 40

Chart or Map
Early June

1.03 cubic miles

0.90 cubic miles

24th / 36 

Chart or Map
Late June

0.76 cubic miles

1.27 cubic miles

9th / 34 

Chart or Map
Early July

1.20 cubic miles

1.59 cubic miles

11th / 39 

Chart or Map
Late July

0.82 cubic miles

1.62 cubic miles

5th / 39 

Chart or Map
Early August

0.26 cubic miles

1.31 cubic miles

1st / 37

Chart or Map
Late August

0.77 cubic miles

1.07 cubic miles

10th / 40

Chart or Map
* The ‘2024 Rank’ column indicates this year’s result rankings, from the least hypoxic (better) to the most hypoxic volume, compared against historical results for each time period. Results are likely higher than reported for July 2024 because stations CB5.3, LE2.3, and CB5.2 in Maryland were not sampled due to mechanical issues with the research vessel and Virginia stations CB7.1N and CB7.3 were not sampled due to adverse weather conditions. Results are also likely higher for early August as mechanical issues with the research vessel prevented Virginia from sampling stations CB5.4, CB5.4W, CB5.5, CB6.1, CB6.2, CB6.3, LE3.6 and LE3.7 in the upper Virginia portion of the Bay.

These monitoring results also provide a comparison to the yearly seasonal forecast by the U.S. Environmental Protection Agency’s Chesapeake Bay Program, U.S. Geological Survey, University of Maryland Center for Environmental Science, and University of Michigan. This forecast, which was released in late June, expected 2024 Chesapeake Bay mainstem hypoxic volume to be 4% higher than the 39-year average, due to increased river flows and resultant higher nitrogen loads from January through May 2024. Results thus far indicate better dissolved oxygen condition than predicted.

Crabs, 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.

Ongoing efforts to reduce nitrogen and phosphorus pollution from industrial and wastewater sources, agricultural land, and cities and towns are aimed at reducing hypoxic conditions in the Bay. In the water, nitrogen and phosphorus fuel algal blooms that remove oxygen from the water when they die off and decompose.

Each year from May through October, the Department of Natural Resources computes hypoxia volumes from the water quality data collected and managed by department staff and the Virginia Department of Environmental Quality. Data collection is funded by these states and the Chesapeake Bay Program (CBP). A joint hypoxia report will be issued later this fall to compare monitored versus forecast results for 2024.

Additional Maryland water quality data and information, including the Department of Natural Resources hypoxic volume calculation methods, can be found on the Eyes on the Bay website.

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