Bay “Dead Zone” Predicted to be Larger Than Normal Due to Heavy Spring Rains

Star Democrat article (2018-06-20) reported that University of Maryland and University of Michigan scientists are predicting a larger-than-average hypoxic (low oxygen) and anoxic (no oxygen) dead zones in the Chesapeake Bay this year. The article noted that the main cause is the heavier than normal spring rainfall. The primary cause of these dead zones is excess nutrient pollution, such as from wastewater, stormwater runoff, or agricultural runoff, that causes algae blooms which then die and leech oxygen from the water as they decompose. Various climate factors, such as rainfall, can also influence the intensity and size of these dead zones.

Despite the larger than normal prediction for this year, Bay restoration efforts are having a positive long-term effect on the dead zones. From the article:

“Despite the forecast, bottom dissolved oxygen concentrations in Maryland’s portion of the Chesapeake Bay mainstem have continued to increase since 2014, and last year we recorded the second-smallest hypoxic volume ever,” said Bruce Michael, director of the Resource Assessment Service at the Maryland Department of Natural Resources. “The bay is rebounding and responding, as seen by record submerged aquatic vegetation totals. Our strategic investments and sacrifices aimed at reducing nutrients and sediment are working, but more can still be done throughout the watershed.”

A Chesapeake Biological Laboratory news release (2018-06-18) provides further information:

This year, the anoxic portion of the hypoxic zone is predicted to be 0.43 cubic miles (1.78 cubic kilometers) in early summer and 0.41 cubic miles (1.7 cubic kilometers) in late summer.

“The Chesapeake Bay’s response to reductions in nutrient pollution may be gradual, involve lags, and be interrupted by the weather,” said report co-author Jeremy Testa of the University of Maryland Center for Environmental Science’s Chesapeake Biological Laboratory. “The forecast illustrates these challenges well.”

Measurements of the Chesapeake Bay’s dead zone go back to 1950, and the 30-year mean maximum dead zone volume is 1.74 cubic miles.

To learn more about the overall health of the Bay and the current and future direction of restoration efforts, attend the “Clear Water: The State of the Bay” general session at the upcoming 2018 MACo Summer Conference in Ocean City, Maryland. The Conference runs from August 15-18.

Learn more about MACo’s Summer Conference: