Flood posing threat to bay area

By Tom Venesky tvenesky@timesleader.comSports Reporter

Most of the sediment, debris and chemicals that flushed through the Susquehanna River during last week’s flood ends up in one place: the Chesapeake Bay. 

That surge of floodwater and everything carried with it presents a wide range of potential impacts to the bay ecosystem, and some of them could be devastating.

On the positive side, the grasses in the bay have already stopped growing and are dying back in preparation for winter. As a result, they won’t be affected by the flood, according to John Surrick, a spokesman for the Chesapeake Bay Foundation.

But other aspects critical to the bay could be severely impacted:

• The oysters that play a vital role in filtering and cleaning the water. An adult oyster can filter as much as 50 gallons of water per day, and it takes one year for oysters to filter the entire bay.

“The sediment coming down the river could smother the oyster reefs. The concern is when the beds get silted over, the oysters – particularly the oyster larvae, don’t have that hard surface to attach to that they need,” Surrick said.

• Surrick said the volume of water coming out of the Susquehanna River has drastically reduced the salinity level in parts of the bay, particularly the upper Maryland portion. Oysters need water with a certain level of salinity to survive, and officials are hoping that levels return to normal soon. Oysters can survive a few weeks in such conditions.

“The big question is how long does the low salinity level remain. Right now the salinity in the upper bay is 1.2 to 1.5 percent, which is very low,” Surrick said.

• The enormous load of sediment, nitrogen and phosphorous carried to the bay by the river presents another problem. Surrick said it could cause a resurgence of dead zones in the bay – areas with oxygen levels too low for most aquatic species to survive.

After Hurricane Irene struck the bay, the resulting winds caused the dead zone to disappear.

“We may see the dead zones reappearing,” Surrick said. “This all ties in to the importance of the bay pollution diet – the limit that the bay can withstand. This kind of event underscores the importance of getting that pollution diet in place and adhering to it.”

• As for the debris, Surrick said it is all over the bay. On Tuesday, one person found a bowling ball floating in the water, he said, adding that a 30-foot tree washed down the river and now floats by his office. “We’re seeing fields of debris coming down the river,” Surrick said.

A wet spring and summer have already contributed to a heavy dose of sediment, pollution and debris into the bay. Surrick said the amount of water that the Susquehanna River poured into the bay by June was equivalent to what it contributes in an entire year.

Although it’s too early to tell if the impact on the bay from last week’s flood is greater than what occurred during the Agnes Flood in 1972, Surrick said the concerns are high.

“The bay is out of balance. The normal things that help to clean it, like oysters, could be significantly impacted,” he said. “The bay is going to be affected by this for some time.”