Bay Anoxia Better than Expected, Maybe

Bay 'dead zone' smaller than predicted this summer

Following what could have been bad news that broke in June for the Chesapeake Bay’s low-oxygen zone, scientists have found that the “dead zone” is “much better than average for early June,” according to the Maryland Department of Natural Resources.

Dead zones are hypoxic areas of the Bay with little to no oxygen, which stresses fish and other Bay life, like oyster and crabs, which need oxygen to support life. They are fueled by excess nutrient pollution, which feeds algae blooms, and when the algae dies it settles to the bottom and absorbs the oxygen in the water.

The dead zone was originally expected to be larger than average this summer, with scientists in June pointing to higher than average spring rainfall amounts in New York and Pennsylvania, and that stormwater would makes its way to the Susquehanna River, which flows south until it reaches the headwaters of the Chesapeake Bay, and this spring brought with it above average nitrogen loads, a nutrient that helps fuel algae growth.

The predictions were made by the National Oceanic and Atmospheric Administration, U.S. Geological Survey, University of Maryland Center for Environmental Science and University of Michigan scientists.

But, dissolved oxygen conditions in Maryland’s portion of the Chesapeake Bay’s main steam were much better than predicted.

“The better-than-average conditions could be partially attributed to sustained westerly winds during the sampling period, which mixed oxygen deeper into the water column in the main Bay channel,” the Maryland Department of Natural Resources stated in a press release dated July 25. “The winds, however, pushed surface waters eastward, allowing lower dissolved oxygen bottom waters to percolate toward the surface on the western side of the lower Bay.”

So the better water in the channel was paid for with more anoxia near the surface on my side? I'm not so sure that's really good news. And maybe it's just a sampling problem.

But, DNR said winds and rough water conditions around a sampling station near the Maryland-Virginia state line, and the lower Potomac station, prevented them from being sampled.

“It should be noted that the absence of data from these stations could produce lower than average estimates of hypoxia,” DNR stated.