The dead zone in the Chesapeake Bay this year is the smallest since monitoring began in 1985, according to data released today by the Maryland Department of Natural Resources, Old Dominion University, and Virginia Institute of Marine Science.
The dead zone appears annually in parts of the Bay and its tidal rivers during warmer months, creating areas where oxygen levels are so low that the water cannot support fish, blue crabs, oysters, and other aquatic life. The dead zone is caused by algal blooms that are fueled by nitrogen and phosphorus pollution. These cloud the water and cause damage, mainly during the warmer months.
The extent of each year’s dead zone is dependent on several factors, including how much nitrogen and phosphorus pollution enters waterways. High precipitation can contribute to the dead zone because it leads to more polluted runoff washing into rivers and streams. Precipitation was below average for most of 2023.
Chesapeake Bay Foundation Virginia Senior Scientist Joe Wood issued the following statement.
“While the smaller dead zone this year is a promising sign, we must remember the major challenges that lie ahead. The mere existence of a dead zone in the Bay is cause for alarm, and a sign that we must still dramatically reduce pollution flowing into the Bay.
“Most of the pollution-reduction progress so far has come from wastewater treatment plants. States in the Bay watershed are still lagging far behind in reducing polluted runoff from agriculture as well as urban and suburban areas. In fact, urban and suburban pollution is increasing.
“Climate change is also making saving the Bay more challenging. The fact that 2023 is on track to be the hottest year on record globally is a red flag, since warmer water holds less oxygen. Polluted runoff from hot pavement increases water temperatures, underscoring the need to reduce runoff from both urban areas and agriculture.
“As climate change also brings heavier and more frequent rainstorms that wash more pollution into our waterways, we can’t count on drier-than-average years to temper the Chesapeake Bay’s dead zone.
“To continue the progress largely made by wastewater treatment plant upgrades, leaders must seek new solutions and invest in efforts that address climate change while reducing pollution from agriculture and stormwater.”