Mercury and other toxic metals have poured into major creeks in the Saluda, Congaree and Broad river basins after sewage systems failed during the past year, researchers at the University of South Carolina have found.
From November 2015 to this past March, USC researchers discovered elevated amounts of metals in wastewater spilling at Stoops Creek and Crane Creek, both of which are large tributaries of Columbia rivers.
The findings, to be presented Friday at a USC conference in Columbia, suggest that metals from sewage spills may be having more of an impact on rivers than previously thought, said USC scientist Sarah Rothenberg, who co-authored the study with other university researchers and Congaree Riverkeeper Bill Stangler.
“You have metals going into the environment that would otherwise have been treated and removed at a wastewater treatment plant,’’ said Rothenberg, an assistant professor in Carolina’s public health school.
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“The fact that this is just going right into the environment .... suggests that it may be a more significant source than previously believed.’’
Stangler, whose organization also monitors water quality in the Saluda and Broad rivers, said the study “raises some questions we need to look into.’’
Much of the testing done after sewer spills in the Columbia area is for bacteria, the pollutant most likely to cause immediate illness, such as upset stomachs in people exposed to contaminated water.
But heavy metals can have long-term impacts on rivers and aquatic life, such as fish. The Congaree River, for instance, is under an advisory for mercury in fish.
The S.C. Department of Health and Environmental Control recommends eating no more than moderate amounts of somes species. People who eat fish polluted with mercury can over time develop a loss of peripheral vision, numbness in their hands and nervous system disorders. Exposure to mercury in the womb can result in brain damage in young children.
Researchers have long attributed mercury in fish to air pollution from coal-fired power plants. Mercury rains back to earth, sinks into rivers and builds up in fish and other organisms.
Rothenberg’s study, to be presented by her student, Maggie Emmons, is being discussed at one of the biggest research conferences organized since an October 2015 flood deluged South Carolina.
The conference, which ironically was postponed by Hurricane Matthew in October 2016, will feature three dozen projects undertaken by Carolina researchers since the big 2015 flood. USC scientists launched the research effort to better understand how the flood occurred, how it affected South Carolina, and what lessons could be learned.
Among the research papers to be presented are studies on how people used Twitter to respond to the flood; how the flood affected Latinos; how mold infested USC buildings after the flood; the way dam failures affected water quality in the Columbia area; and what impact the flood had on bridges.
Last year’s flood swamped parts of Richland and Lexington counties, breaking dams and sending thousands of people fleeing for safety. More than 50 state-regulated dams broke across South Carolina, most of which were in the Columbia area. More dams broke in eastern South Carolina during Hurricane Matthew in October.
“It is our collective goal that, the next time a natural disaster threatens the Palmetto State, we will be better prepared to face and overcome the challenges it brings with it,’’ USC vice president for research Prakash Nagarkatti wrote in a summary of the research projects.
The Rothenberg-Stangler study began as a project examining water quality after the flood, but broadened as researchers found sewage spilling in several areas. Researchers found high concentrations of 16 heavy metals at a ruptured sewage main. At another spot they discovered elevated levels of 38 metals in an area where sewage overflowed.
Some mercury levels were higher in the wastewater overflowing into Crane Creek than in the creek downstream, researchers found.
“Our preliminary results indicated sanitary sewage overflows were a signficant source of metals, including methylmercury, to the Congaree watershed, which should be investigated further,” according to an abstract of the Rothenber-Stangler study.