It's no secret that access to drinking water can be limited during severe weather events. But what about the days and weeks that follow? According to research from Clemson's Belle W. Baruch Institute of Coastal Ecology and Forest Science, water can still be unsafe weeks after residents' access to water has been restored.
Dr. Hamed Majidzadeh, a post-doctoral fellow at the Baruch Institute, is one of several National Science Foundation-funded researchers who have studied the impact severe rain events like South Carolina's flood of 2015 and Hurricane Matthew in 2016 have on water quality.
"We had two hurricanes in South Carolina, one year apart exactly, in October 2015 and October 2016," Hamed said, referring to Hurricanes Joaquin and Matthew. "Hurricanes are not good, but having two hurricanes one year apart, exactly at the same time, provided us with a great opportunity to see how they impact the water quality, how lasting they are, [and] how many days after a hurricane event we should watch the water quality."
Hamed and his colleagues particularly focused on the increased quantities of carbon, nitrogen and organic matter found in drinking water after these events. Carbon and nitrogen might seem harmless enough, but their interaction with other chemicals that pose serious issues.
"During water purification, we form these disinfection byproducts . . . chloroform is probably the most well-known one, and they are a threat to human health because they can cause, for example, cancer," explained Dr. Alexander Ruecker, one of Hamed's colleagues.
Essentially, carbon and nitrogen reacts with chlorine during the water purification process in water treatment facilities, resulting in an uptick in harmful disinfection byproducts like chloroform in drinking water. These chemical byproducts have the potential to harm other creatures as well.
"[An] exceeding amount of nitrogen in the water can deoxygenize water and endanger the aquatic life," Hamed explained, noting the potential danger to fish and other animals, both large and small.
Although they have studied these conditions since 2015, Hamed said his team isn't qualified to make a judgment call about how water treatment facilities and local governments should react to this information. Appropriate public policy, Hamed said, should be determined by public officials, after consulting the science uncovered by himself and others.
However, Hamed also said that their results are certainly concerning.
"We have the flooding, people evacuate and the physical damage ends . . . but the changes in water quality can be continuously extended after that. It can continue for twenty days, for thirty days after we have the flooding resulted from hurricanes," Hamed said. "In this case, for Hurricane Matthew and Joaquin . . . up to 20 days after the hurricane we had extended increase in carbon and nitrogen, which can form disinfection byproducts above levels that are considered safe by the EPA [Environmental Protection Agency]."
These statistics, notably, refer to specifically to conditions in coastal areas. Hamed's research indicates that the concentrations of carbon and nitrogen gradually taper off moving away from the coast, for the simple reason that there are more wetlands in coastal areas.
According to Hamed, wetlands are highly absorbent of carbon, and export massive quantities of carbon into the ocean each year. During intense flooding, wetlands that are connected to river systems export massive quantities of carbon into river systems, which finds its way into drinking water.
Fortunately, because the researchers collected water samples both during and after rain events, they were able to develop a metric for what wetland areas should expect during future events.
"In the future, depending on the intensity of the hurricane event and the location of the hurricane event, we can predict how the water quality will be changed, and we might be more prepared for that," Hamed said.
Dr. Alexander Ruecker, Hamed's aforementioned colleague, agreed that more research was merited to study future events.
"We will probably see this kind of severe weather event—such as hurricanes, flooding—more frequent in the future. Also, we just need more data . . . it would be very interesting to follow up in the future," he said.
In fact, the weather events of the past month have already given the Clemson researchers the opportunity to do just that. In the time that has passed since our interview, they have collected water samples in Texas during Hurricane Harvey and in South Carolina during Irma. Hamed also said that he and his team are examining methods to reduce the flow of carbons, nitrogen and other pollutants such as mercury into streams.
Hamed and other Baruch Institute faculty also continue to collaborate with other scholars who have investigated the environmental effects of hurricanes in the region, including researchers at Coastal Carolina University and the University of North Carolina Greensboro to educate the public about the extended effects of extreme weather events on daily life.
Note: This story has been edited to reflect the correct name of Clemson's lab at the Baruch Institute. This story previously incorrectly identified the program as "The Belle W. Baruch Institute of Coastal Ecology and Ocean Science." The correct name for this program is the "Belle W. Baruch Institute of Coastal Ecology and Forest Science." The University of South Carolina operates the marine lab at the Baruch Institute, the Belle W. Baruch Institute for Marine and Coastal Sciences.