ANNAPOLIS, Md. – Water monitoring data collected by the Maryland Department of Natural Resources (DNR) and Old Dominion University show that dissolved oxygen conditions in the Chesapeake Bay mainstem of Maryland and Virginia were slightly better than average in August 2022, with early and late August having less hypoxia than usual.
The hypoxic water volume — waters with less than 2 mg/l oxygen — was 1.34 and 0.98 cubic miles during early and late August monitoring cruises, compared to historical early and late August averages (1985-2021) of 1.37 and 1.08 cubic miles.
Both cruises’ hypoxia results were near the historical median rank of the past 38 years. Additionally, a volume of 0.3 cubic miles of anoxia (waters with less than 0.2 mg/l oxygen) was observed in early and late August, which is slightly more than average.
Chesapeake Bay hypoxia laterally constricted in August, and through the month progressively dissipated from Virginia waters and the lower Maryland Chesapeake Bay. Freshwater inflows to the Bay, as estimated by the U.S. Geological Survey, were lower than average and near the historical lower 25th percentile. Lower inflows usually deliver less nutrients to the Bay, resulting in better dissolved oxygen conditions and could partly explain the near and above average conditions this summer.
Maryland and Virginia combined results are presented for the mainstem Bay to be more comparable to the yearly seasonal forecast by the U.S. Environmental Protection Agency’s Chesapeake Bay Program, USGS, University of Maryland Center for Environmental Science, and University of Michigan.
The 2022 forecast, released in late June, expected Chesapeake Bay mainstem hypoxic volume to be 13% lower than the 37-year average due to reduced river flows from January through May 2022, as well as less nitrogen carried to the Bay because of nutrient management efforts. Maryland and Virginia’s monitoring results thus far have matched the forecast of better-than-average conditions.
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.
Each year from May through October, DNR computes hypoxia volumes from the water quality data collected by DNR and the Virginia Department of Environmental Quality.
Data collection is funded by these states and the Chesapeake Bay Program. Bay hypoxia monitoring and reporting will continue through the summer. Additional Maryland water quality data and information, including DNR’s hypoxic volume calculation methods, can be found at DNR’s Eyes on the Bay website.