Bay had smallest ‘dead zone’ on record for early July
Hurricane Arthur may have produced a rainy 4th of July for beachgoers, but its winds brought some good news for Chesapeake Bay water quality.
The Maryland Department of Natural Resources reported that the oxygen-starved dead zone observed in early July was the smallest for that period seen in 30 years of water quality monitoring.
That’s a sharp contrast to the slightly worse-than-normal oxygen conditions that scientists has predicted in the wake of higher-than-average water flows and nitrogen levels that entered the Bay from the Susquehanna River during the early spring.
The reason for the change, according to DNR scientists, is that when Arthur passed along the coast, winds associated with the hurricane mixed the low-oxygen waters on the bottom of the Bay with the oxygen-rich water on the surface.
Without that mixing, the bottom areas of the Bay typically become oxygen-starved, or hypoxic, as algae die, sink to the bottom and are decomposed by bacteria that remove oxygen from the water.
Prior to Arthur, the Bay was indeed on track for worse-than-average oxygen conditions. And scientists cautioned that oxygen levels were expected to worsen by late July, baring any further unusual weather events.