The latest data from the Maryland Department of Natural Resources and Old Dominion University indicate that dissolved oxygen conditions in the Chesapeake Bay’s mainstem in Maryland and Virginia worsened in May 2024. Regular monitoring cruises conducted aboard research vessels collected these samples.
In May 2024, the hypoxic water volume, defined as waters with less than 2 mg/l of oxygen, reached 0.42 cubic miles, surpassing the May average of 0.18 cubic miles recorded from 1985 to 2023. This figure ranks as the sixth largest volume of hypoxic water recorded for this period. Notably, no anoxia, which refers to areas of water with less than 0.2 mg/l of oxygen, was observed during the May 2024 monitoring cruise. The combined mainstem Bay monitoring results for Maryland and Virginia provide a comparison to the yearly seasonal forecast by the U.S. Environmental Protection Agency’s Chesapeake Bay Program, the U.S. Geological Survey, the University of Maryland Center for Environmental Science, and the University of Michigan.
In late June, this forecast anticipated that the hypoxic volume in the Chesapeake Bay’s mainstem would be 4% higher than the 39-year average, attributed to increased river flows and resultant higher nitrogen loads from January through May 2024. The survival of crabs, fish, oysters, and other creatures in the Chesapeake Bay depends on sufficient oxygen levels. Therefore, scientists and natural resource managers closely study the volume and duration of Bay hypoxia to assess potential impacts on bay life.
Efforts are ongoing to reduce nitrogen and phosphorus pollution from industrial and wastewater sources, agricultural land, and urban areas to mitigate hypoxic conditions in the Bay. Nitrogen and phosphorus in the water promote algal blooms, which deplete oxygen when they decompose. From May through October each year, the Department of Natural Resources calculates hypoxia volumes using water quality data managed by department staff and the Virginia Department of Environmental Quality. The Chesapeake Bay Program funds these data collection efforts, along with the states involved. Monitoring and reporting of Bay hypoxia will continue throughout the summer. Additional Maryland water quality data and information, including the Department of Natural Resources’ hypoxic volume calculation methods, are available on the Eyes on the Bay website.
