Superstorm Sandy devastated New York City and New Jersey and left millions of people without power. But the storm will likely cause less harm to the Chesapeake Bay than past major storms, like Hurricane Agnes in 1972, or last year’s Hurricane Irene and Tropical Storm Lee, whose rains flushed vast quantities of mud, debris, and other pollutants into the Chesapeake Bay, according to Dr. Beth McGee, Senior Scientist with the Chesapeake Bay Foundation.
Sandy dumped less rain than these previous storms upstream from the Bay in Pennsylvania, in the watershed of the Susquehanna River, the Chesapeake's largest tributary. At the Conowingo Dam on the Susquehanna River this week, water levels hit 19 feet. That was significantly lower than flood stage, which is 23 feet, and also lower than the 32 feet the waters hit during Hurricane Irene last year, according to U.S. Geological Survey.
“There was a lot less runoff this year,” said Dr. McGee. “We don’t expect to see much of an effect on the Chesapeake Bay proper. But we might see a lot of erosion on the smaller streams and low lands on the Eastern Shore.”
The National Oceanic and Atmospheric Administration (NOAA) Chesapeake Bay Office reported that because the winds were primarily from the north, the storm did not blow a big surge of water up the Bay that would have severely flooded cities and towns in Maryland and Virginia (as might have happened if the winds had the winds been blowing from the south). "While parts of New Jersey, New York, and the southern New England coast dealt with crippling storm surge, for the most part, the Chesapeake Bay avoided surge-related flooding, though some coastal flooding was reported," NOAA reported. "
There was, however, a huge push of water into Manhattan, where millions remain without power or mass transit. Eyeing this devastation, Mike Tidwell, founder of the Chesapeake Climate Action Network, published an article in The Nation that proclaimed: "We are all from New Orleans now. Climate change—through the measurable rise of sea levels and a documented increase in the intensity of Atlantic storms—has made 100 million Americans virtually as vulnerable to catastrophe as the victims of Hurricane Katrina were seven years ago."
Back in the Chesapeake region, some scientists feared that the water pollution resulting from the “double whammy” of Hurricane Irene and Tropical Storm Lee in August and September of 2011 would worsen the Bay’s low oxygen "Dead Zone" during the summer of 2012. But that did not happen, according to Dr. McGee. Water clarity in the Bay suffered in the short term because of all the silt and mud. But the nitrogen and phosphorus pollution from stormwater runoff did not cause a long-term impact on the Chesapeake.
In fact, the dead zones in the Bay this past summer were at their second lowest level since monitoring began in 1985 (second only to that first year), according to the Maryland Department of Natural Resources. About 16.7 percent of the water in the Bay this past summer had low-oxygen conditions (less than 2 parts per million dissolved oxygen in the water, which can be deadly to fish) compared to more than 25 percent of the Bay during June through August of 2011.
This could be a sign that reduced pollution into the Bay over many years is helping the estuary’s ability to bounce back from storms. “We are hopeful we will see an improved resilience with this ecosystem, so that when these events occur…the Bay can recover more quickly,” Dr. Donald Boesch, President of the University of Maryland Center for Environmental Science, told WYPR public radio.
Underwater grasses -– which were buried in mud by the massive Hurricane Agnes in June 1972 -– will probably not be wiped out by Superstorm Sandy, Dr. McGee said. The plants normal lifecycle means that they have already disappeared for the season by late October.
Beyond silt and runoff pollution, storms often also trigger power failures and overflows at municipal sewage treatment systems.
On Monday, Superstorm Sandy knocked out Howard County’s sewage treatment facility in Savage, Maryland, causing a spill of about 20 million gallons of sewage and rainwater to gush into the Little Patuxent River, a Chesapeake Bay tributary. This was the largest of about 19 sewage spills reported across Maryland during the storm, according to The Baltimore Sun.
But even all these are minor in comparison to the spills during Hurricane Irene last year, which included more than 100 million gallons of sewage released during the rupture of a sewer main into the lower Patapsco River, the newspaper reported.
For details on how much rain and snow fell during Superstorm Sandy, click here.
By Tom Pelton
Chesapeake Bay Foundation
(Photo from NASA)