During last summer's Hurricane Irene, the worst storm to hit the New York area in 200 years, record amounts of dissolved organic matter were found in Catskill waters and in the Ashokan Reservoir that supplies New York City with drinking water, they said.
The Catskill Mountains watershed is a primary source of drinking water for New York City, and over a two-day period in late August Irene dropped over 11 inches of rain, 17 percent of the average annual rainfall, on one of the creeks that feeds the Ashokan.
"This is the biggest rain event ever sampled for the region," Yale doctoral student Bryan Yoon said, noting the volume of water discharged by Esopus Creek increased 330-fold, sending an unprecedented amount of dissolved organic matter to the Ashokan.
Excessive amounts of dissolved organic matter could lead to numerous environmental problems, Yoon said.
Dissolved organic matter binds with metal pollutants and transports them, interferes with ultraviolet processes that reduce pathogens in water, affects aquatic metabolism and leads to the formation of carcinogenic disinfection byproducts, he said.
"All of those problems become more serious as larger quantities of dissolved organic matter are transported to lakes and coastal systems," Yoon said. "Hurricane Irene was a prime example that there is no limit to the amount of dissolved organic matter that can be exported by extreme rain events."