Below-average ‘Dead Zone’ Anticipated for Chesapeake Bay in 2015

The Swamp Stomp

Volume 15, Issue 32

A research team from the University of Michigan forecasted a marginally below–average “dead zone” for this summer in the Chesapeake Bay.  While the results were only slightly lower than normal, it is still a significant finding for the nation’s largest estuary.

Released on June 23, 2015, by the National Oceanic and Atmospheric Administration, the 2015 Chesapeake Bay forecast indicates an oxygen-depleted, or hypoxic, region of 1.37 cubic miles–roughly 10 percent less than the long-term average.

The annual hypoxic region, or “dead zone,” in the Chesapeake Bay normally results due to farmland runoff containing nitrogen and phosphorus from fertilizers and livestock waste. Once areas become contaminated, fish and shellfish either leave the oxygen-depleted waters or die. Subsequently, “dead zones” threaten the bay’s production of crabs, oysters, and other important fisheries.

“These annual forecasts help to remind federal and state policymakers and the public that insufficient progress is being made to reduce the size of these low-oxygen regions,” said aquatic ecologist Don Scavia, director of the University of Michigan’s Graham Sustainability Institute. “The size of annual Chesapeake Bay dead zone has changed little over the past decade, which underscores the need for persistent management action to reduce the amount of nutrients flowing into the bay. The Environmental Protection Agency must keep states’ feet to the fire.”

Based on models developed by NOAA-sponsored researchers at the University of Michigan and the University of Maryland’s Center for Environmental Science, the hypoxia forecast works both with the nutrient-level estimates and stream flow data provided by U.S. Geological Survey (USGS). The USGS estimates indicate that only 58 million pounds of nitrogen were transported to the Chesapeake Bay between January and May 2015—29 percent below average amounts.

The predicted size of the “dead zone” is a result of the low river flow and below-normal nutrient loading from the Susquehanna River.

USGS associate director for water, William Werkheiser said, “Tracking how nutrient levels are changing in streams, rivers and groundwater, and how the estuary is responding to these changes is critical information for evaluating overall progress in improving the health of the bay. Local, state, and regional partners rely on this tracking data to inform their adaptive management strategies in bay watersheds.”

Besides nutrient-rich waters flowing into the bay, wind speed and direction, precipitation amounts, and temperature also affect the size of “dead zones.” In 2014, the sustained winds from Hurricane Arthur mixed the hypoxic zone water with the water, and oxygen, in the rest of the bay and dramatically reduced the “dead zone” to 0.58 cubic miles.

Donald Boesch, president of the University of Maryland Center for Environmental Science, claimed, “Forecasting how a major coastal ecosystem, the Chesapeake Bay, responds to decreasing nutrient pollution is a challenge due to year-to-year variations and natural lags. But we are heading in the right direction.”

Kathryn Sullivan, undersecretary of commerce for ocean and atmosphere and NOAA administrator, added, “These ecological forecasts are good examples of critical environmental intelligence products and tools that NOAA is providing to stakeholders and interagency management bodies such as the Chesapeake Bay Program. With this information, we can work collectively on ways to reduce pollution and protect our marine environments for future generations.”

If accurate, these predictions indicate that attempts to create healthier, less polluted waterways may be starting to pay off.

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