A yoga mat, truck tires, a basketball and the seat from a portable toilet. Those items and thousands more are floating down the Chesapeake Bay, which is receiving flood waters from the Susquehanna and other rivers swollen by rains from the remnants of Tropical Storm Lee.
Rain wasn't falling Monday, but just above the Bay Bridge, the debris from the storms was still coming down the bay. Seagulls, sandpipers and other birds were resting on the floating logs, bags and toys under sunny skies, flitting above the now muddy waters of the bay.
The flood waters are bringing sediment, spilled sewage, fertilizer and other pollutants, scientists said, threatening bay grasses and species such as oysters that are key to keeping the waters clean.
One bright spot is that Lee followed closely after Hurricane Irene, which also brought pollutants into the bay, but stirred low-oxygen areas known as dead zones, said John Page Williams, a senior naturalist with the Chesapeake Bay Foundation.
Last week's rains have now put a sheet of muddy fresh water on top of the bay's saltier water. That means dead zones can grow again if the fresh muddy water remains too long on top of the saltier water below, where bacteria could consume oxygen as they break down dead algae.
“Irene broke up the dead zones, which is great,” Williams said. “This shoved the lid back on.
“So, pray for wind,” Williams said as he piloted a boat around the mats of debris.
The Chesapeake Bay Program, the regional federal-state partnership that coordinates restoration efforts, said 2011 will most likely be one of the highest annual flow years on record from the Susquehanna River into Chesapeake Bay because of the storms and a wet spring across the watershed. The bay's watershed drains parts of Maryland, Virginia, West Virginia, Pennsylvania, Delaware and New York.
To track the impact of the storms on the bay, the nation's largest estuary, the United States Geological survey is taking samples and analyzing them for bacteria, pesticides and trace metals.
The sheer volume of flood water is going to have a negative impact on the bay, but the timing of the storms late in the seasons will mitigate the damage because the main growing season for grasses has passed along spawning seasons for many species. Summer temperatures also help fuel algae blooms that are fed by fertilizer, sewage and other so-called nutrients, the Chesapeake Bay Program said.
However, the scouring of the bay bottom in the Susquehanna Flats area near the mouth of the river, a key area for underwater grasses, and also in the upper tidal Potomac, are areas of concern. The bay's oysters, which filter bay water but cannot move off their bars, are also at risk from sediment that could bury them and too much fresh water.
Despite the setback the flooding may represent to bay restoration efforts, Williams said the U.S. Environmental Protection Agency' “pollution diet” strategy for restoring the nation's largest estuary is as important as ever. One of the key goals of the strategy is to reduce the amount of water that runs off land during storms.
“All of that is going to tend to moderate the extremes of storms like this,” Williams said.