The ideal ecosystem to expose people to dangerous amounts of mercury requires rainy skies, a mix of industry and swamp and a culture where people have a taste for seafood.

Louisiana, of course, fits the bill. Health officials warn of mercury that may be in fish caught in many of the state’s rivers and bayous, including the Amite River and its tributaries in the Baton Rouge area.

But the advisories flagging those waterways area based on old data, since the state stopped testing for mercury amidst Jindal-era budget cuts at the Department of Environmental Quality.

Carefully piloting a boat in the Atchafalaya River Basin on a recent morning, the state Depa…

Testing has since resumed, funded by $1.5 million paid by power company NRG Louisiana Generating in lieu of a fine. Now, just over a year since the first samples were taken, results have begun coming in that could soon let doctors, diners and fishermen know whether the waters are any safer.

State regulators are reviving a once-successful program to test the mercury levels of fish c…

Mercury starts out in coal. Particles are released when it burns and enter the atmosphere, falling back down to earth in a manner similar to acid rain, explained DEQ senior environmental scientist Al Hindrichs. Mercury can also be a by-product of some chemical plants, and it was once used in equipment that measures the pressure in pipelines.

Certain bacteria chemically change mercury so it can enter the food chain. The bacteria are most abundant in swamps and other low-pH bodies of water, Hindrichs explained.

The pH of pure water is 7. In general, water with a pH lower than 7 is considered acidic.

The creatures at the top of the food chain have the highest concentration of mercury. It's in the fillets of game fish such as bass and crappie. Doctors generally allow at least a meal or two every month even from water where mercury has been found. However, the prohibitions are stricter for children and women who may become pregnant due to the threat of neurological damage to growing bodies.

More than 50 bodies of water in Louisiana have some sort of advisory about eating fish caught from them. In most cases, mercury is the primary worry, though there are other concerns. Bayou Baton Rouge, Devil's Swamp and even Capitol Lake have all been flagged for other chemical pollutants.

A state Department of Health spokesman said the agency is aware of the ongoing mercury testing but hasn't received any results yet. Hindrichs said that without analysis, it's impossible to guess whether mercury concentrations have gone up or down or stayed the same.

Mercury is hard to predict because it can come to Louisiana from around the world, said Hindrichs and DEQ spokesman Greg Langley. The mercury that falls in local water may come from coal burned in Louisiana or in China, and there's no chemical signature to point to its origin.

Testing is set to continue for several more years, and scientists plan to check the fish at all the sites currently under advisement. Crews began around Lafayette and have since moved to the waters of the Lake Charles area. After that, there are plans to visit the Florida Parishes, Hindrichs said.

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