Scientists expect low river flow and reduced nutrient-rich runoff from the Susquehanna and Potomac Rivers this spring to result in an average to slightly smaller-than-average dead zone in the main stem of the Chesapeake Bay this summer.
Aquatic life—from blue crabs to underwater grasses—relies on dissolved oxygen to survive. When nutrient-fueled algae blooms die and decompose, the resulting areas of little to no oxygen, known as dead zones, can suffocate underwater plants and animals. The latest forecast predicts a mid-summer hypoxic, or low-oxygen, zone of 1.58 cubic miles: close to the long-term average. The anoxic, or no-oxygen, zone is expected to reach 0.28 cubic miles in early summer and grow to 0.31 cubic miles by late-summer.
This forecast, funded by the National Ocean and Atmospheric Administration (NOAA), is based on models developed at the University of Maryland Center for Environmental Science and the University of Michigan and relies on estimated nutrient loads from the U.S. Geological Survey (USGS). According to USGS, 66.2 million pounds of nitrogen entered the Chesapeake Bay in from January to May 2016, which is 17 percent lower than average nitrogen loadings.
Over the next few months, researchers with the Maryland Department of Natural Resources (DNR) and the Virginia Department of Environmental Quality (DEQ) will monitor oxygen levels in the Bay, resulting in a final measurement of the Bay’s dead zone later this year.