Scientists find ‘alarming' levels of toxic metals, pollution in Lake Maurepas

Yahoo

19-06-2025

Cypress trees remain in the wetlands and swamps of Lake Maurepas. (Wes Muller/Louisiana Illuminator)
Scientists at Southeastern Louisiana University have found dangerously high levels of toxic metals and other contaminants in Lake Maurepas and have traced most of the pollution to industrial and other human activities.
Led by SLU chemistry professor Fereshteh Emami, a team of researchers analyzed 400 water and sediment samples collected from multiple locations and depths in the lake from June through December 2023 and developed new methodologies to trace the origin of the pollutants, track how they spread and determine the factors that make them worse. The results were 'alarming,' according to the study, which was published in Environments in November and accepted for publication in another scientific journal, ACS Omega, this month.
The analysis revealed concentrations of heavy metals and nutrients far beyond the thresholds the Environmental Protection Agency considers safe. Arsenic levels peaked at 420% above the safe limit for lakes and 6,300% over the EPA's drinking water threshold. Lead and cadmium were detected at similarly high levels averaging orders of magnitude above safe limits. Nickel, copper, and manganese concentrations were also observed above their respective safety thresholds.
Heavy metal exposure is known to cause severe health problems and can be fatal to humans.
'I was just surprised how polluted the area is,' Emami said in an interview.
Emami's team at Southeastern developed new methodologies that allowed them to trace the pollutants to Pass Manchac and three rivers that feed into Lake Maurepas: the Blind, Amite and Tickfaw. It indicated that industrial and agricultural activities are major sources of the pollution.
The researchers also detected a spike in contaminants near Pass Manchac following the Oct. 23, 2023, 'super-fog' multi-vehicle pileup on Interstate 55, indicating that toxic chemicals from combustion vehicles are also running off into the lake.
The heavy metal concentrations found in Lake Maurepas are similar to those later detected following breaks in the waste containment levees at the Atlantic Alumina (Atalco) facility in Gramercy last year. Atalco's toxic metals — which also included arsenic, cadmium and lead, among others — ended up in a public drainage system that flows into the Blind River Swamp of Lake Maurepas.
Although Emami's new methodologies did not trace the pollutants to specific facilities, news of the Atalco incident brought to light a previously unknown event that aligns with their findings, at least anecdotally, Emami said. More sampling and analysis is needed deeper upstream into those rivers in order to further narrow down the sources, she said.
The researchers found other contaminants in the lake, including high levels of nitrogen, phosphorus and a parameter called chemical oxygen demand, which indicates the presence of organic pollutants in water. According to the study, all three parameters were elevated at averages beyond what is considered safe. Their methodologies traced these pollutants to urban runoff and agriculture.
The samples contained other toxic metals, such as mercury, at levels that were within safe limits. But the study noted they still pose a threat to humans and the environment through bioaccumulation, in which low doses of a heavy metal can amass in a living organism over time and add up to a dangerous level.
'Because of the non-biodegradable and bioaccumulative nature of these heavy metals, they could accumulate and biomagnify in fish and other aquatic animals,' the researchers wrote. 'As a result, they could enter the human body eventually through the food chain.'
Emami said mercury is particularly dangerous because it easily bioaccumulates in crops and animals such as fish. Her team is conducting a follow-up study in which they are testing aquatic samples from Lake Maurepas and surrounding rivers for heavy metals and other contaminants such as polyfluoroalkyl substances (PFAS), known as 'forever chemicals.'
Corinne Gibb, a chemist who works for the environmental advocacy Louisiana Bucket Brigade and was not involved in the study, said the research very clearly points to pollution that is flowing into Lake Maurepas from other water bodies.
'What they're showing for sure is that the pollution is coming through those rivers,' Gibb said.
A Louisiana refinery spilled toxic waste into the community and knew about it for months
Southeastern has been monitoring Lake Maurepas since the proposal of a carbon sequestration project by Air Products & Chemicals. The company plans to use carbon capture technology to trap emissions from an $8 billion hydrogen manufacturing complex in Ascension Parish and take them by pipeline to Lake Maurepas, where Air Products will have the capacity to inject an estimated 5 million tons of CO2 per year about a mile below the lakebed.
In the first half of 2023, Air Products performed seismic testing to map the geological formations under the lake. In August of that year, the company moved a large temporary drilling rig into Lake Maurepas that served as a test well for the collection of core and fluid data, which ended in early 2024.
Emami's team initially suspected but were ultimately unable to link any chemical pollutants to Air Products' activity in the lake. Aside from providing a multi-million dollar funding grant, the company played no role in any aspects of the study, its design or the decision to publish the results.
'We're committed to protecting the Lake Maurepas environment and ecosystem, which is why we have supported the independent monitoring of the Lake,' Air Products spokeswoman Christina Stephens said Wednesday after learning about the SLU study's findings. 'It's important for people to understand the lake's ecosystem, and as our work progresses we will continue to operate in a safe and responsible fashion.'
That still doesn't assuage concerns of some local lawmakers. Rep. Kim Coates, R-Ponchatoula, who ran for office on a platform of protecting Lake Maurepas, pointed out the study shows the baseline water quality of the lake is already deeply concerning and could be made worse with general disturbances that accompany lakebed drilling and similar industrial activities.
'Adding deep geological carbon sequestration to an ecosystem already under strain from nutrient pollution raises serious questions,' Coates said. 'Even well-intentioned projects can have unintended consequences in such a delicate and dynamic environment. Until more is known, extreme caution is not just warranted — it's essential.'
SLU's study is the first of its kind to combine dynamic statistical models with water quality data to trace pollutant sources and their driving factors. This allowed Emami's team to provide a comprehensive assessment of the chemical composition of Lake Maurepas based on a wide array of data. The methodology can also be used to predict when and where pollutants will flow or migrate to other areas, she said.
'Using the models, we were looking for the origins of the pollutant sources, and I wanted to know if the pollution sources in the Blind River could [let us] predict what was gonna show up in Manchac,' Emami said. 'And it did.'
Emami said Pass Manchac's significant tidal exchange between Lake Maurepas and Lake Pontchartrain has allowed her team to conclude that the water quality and levels of pollution between the two estuaries are virtually the same.
Until the start of Southeastern's research, there was no ongoing public monitoring for toxic metals in Lake Maurepas.
Louisiana Department of Environmental Quality spokesman Matthew Day said the public should be aware of existing fish consumption advisories, such as one issued last year for Lake Maurepas based on elevated mercury levels detected in fish tissue. However, the agency does not conduct any regular heavy metal monitoring in Lake Maurepas because it is not required under Clean Water Act obligations, Day said.
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