Sandy Was No Treat for Chesapeake Bay
Sandy was forecast to bring the kind of days Noah knew, with wind, rain and water overwhelming land and livers. Coastal New Jersey and New York sampled a day of floods of biblical proportion. Thank God it wasn’t 40 days.
Chesapeake Country got off easy. Winemaker John Autrey of Huntingtown called Sandy “a wimpy storm.”
Scientific sampling is reaching the same conclusion.
“Less flooding and flow of nutrients than from last year’s storms: That’s what the monitoring is showing now,” reports Chesapeake Bay Program’s Margaret Enlow.
Both the U.S. Geological Survey and Maryland Department of Natural Resources had two-person teams out throughout the storm until November 2, collecting “storm event samples” to measure the amounts of nitrogen and phosphorus coming into our rivers and Bay.
Last year on August 31, over 80 U.S. Geological Survey stream gages measured record peaks on rivers and streams in 10 states, as a result of Hurricane Irene’s rainfall.
Two weeks later, Tropical Storm Lee hit. The two storms dumped more than two feet of rain in the Chesapeake watershed.
That was big water.
Water from the upper watershed flowed through the Conowingo Dam into the Bay from the Susquehanna, its mother river, at 775,000 cubic feet per second.
At crest November 1 this year, the Susquehanna’s anticipated flow was 174,000 cubic feet per second.
In Chesapeake Country, Sandy isn’t setting any records.
This year won’t see the scouring of sediment that’s gathered below the big dam over its 90-some years in existence.
Flows over 400,000 cubic feet per second stir up that dirt and debris and hurl it over the dam. Irene and Lee’s after-waters trashed the Bay in ways our 2012 Halloween storm couldn’t rise to.
The Susquehanna’s basin is twice as big as any other Bay river’s, so its effect is largest.
The second largest river, the Potomac, was more affected by this storm than by Irene and Lee. At Washington, D.C., the Potomac peaked at 137,000 cubic feet per second.
The much smaller Patuxent peaked October 30 at almost 7,000 cubic feet per second
Heavy rains on the Eastern Shore drove the Choptank to almost 5,000 cubic feet per second at peak, about half of last year’s high after Irene and Lee.
That’s a lot less water, hence a lot less pollution from sediment and the nutrients that flow from fertilized farm fields and lawns and all our impervious surfaces.
Tricks, Nonetheless
That’s good news, but it’s not the whole story.
For over 24 hours, rain surrounded us as if it were a new atmosphere. We saw it pour from our roofs, overwhelming our downspouts and rain barrels. We saw it puddle in fields, fill up every hole it could find, overflow drainage ditches, run down hills, sidewalks and driveways into our roads and storm sewers.
More than ever before, Sandy opened my eyes to the flow of stormwater all around us.
It was, of course, my namesake storm. But that wasn’t the only reason for my increased awareness. I’ve also been visiting stormwater management systems throughout Chesapeake Country, at homes and businesses in town and in the country. I’ve seen little rain gardens like one at St. Martin’s Lutheran School that eases the flow of water behind Bay Weekly’s Spa Road office; and big ones like the ravine water stopper at Homestead Gardens. I’ve seen urban rain gardens and sidewalk redesign of the sort Spa Creek Conservancy built at Annapolis Hyundai and is designing for Pinkie’s Liquor.
Sandy topped them all.
“Stormwater management systems stop runoff very well if the flow is less than an inch,” says Bruce Michael of Maryland Department of Natural Resources. “Five, seven, 10 or 12 inches of rain overwhelms anything we can do to hold water out.”
Should we then give up? Should we bow out, allowing that nature’s too big for us to manage? Should we overthrow government programs to restore the Bay, from our own flush tax to federal Bay diets that trickle restrictions down to states, counties and cities.
No! say the scientists who see how it all comes together.
“We need to continue to do everything we can for the more normal routine events we have,” says Michael.
The best means management strategies like Best Management Practices and cover crops on farms, urban storm water management projects; silt fence; wastewater treatment plants brought up to the highest possible technology; restricting new septic systems and upgrading existing ones. It means doing our part and pushing our local governments to do more.
Hope from the Storms
When we do our work, sometimes nature works with us.
This was a very dry year, Michael notes, meaning very little pollution was coming in.
Despite the enormous effects of Irene and Lee late last summer, the Bay bounced back. This summer, the Bay had the second-best dissolved oxygen numbers in its mainstem since 1985.
From data like that, we can take hope.
“Chesapeake Bay doesn’t have a long-term memory,” Michael concludes. “It will not take years. If we get our nitrogen and phosphorus down, the Bay will respond quickly.”
Sandra Olivetti Martin
Editor and publisher; [email protected]