Fish advisories indicate local mercury, PFOS contamination in nearby waterways

The 2021 fish advisory recommends limits on fish consumption in areas where fish were found to have high levels of toxins. The toxins that affect fish in Morgan, Lawrence and Limestone counties are mercury and perfluorooctane sulfonate, or PFOS.

At high levels, according to the Centers for Disease Control and Prevention, mercury “may damage the brain, kidneys, and developing fetus.”

Studies have found links between PFOS, which was used in several Decatur industries until the chemical was phased out in 2002, and various conditions, according to the CDC. Among these condition are high cholesterol levels, liver damage, decreased vaccine response in children, high blood pressure, decreased infant birth weight, kidney cancer and testicular cancer.

Both PFOS and mercury build up in the tissue of exposed fish, and also build up over time in human tissue and organs if ingested, according to the Alabama Department of Public Health.

The fish advisory places recommended limits on the number of meals a person should eat of fish caught in the affected waterways. A “meal” as defined in the advisory is 8 ounces of fish.

“The 8 ounces was an agreed upon portion size, probably at the time a ‘normal’ meal size,” said John Guarisco, environmental toxicologist with ADPH, of the guidance that was developed in 2000. “I realize that there are people out there who eat way more than that, and then there’s people out there who eat less than that.”

Guarisco said EPA serving recommendations do not differentiate between typical male and female eating habits but noted the agency does advise that children be limited to 3 ounces of fish from contaminated sources rather than 8 ounces.

“That’s about the equivalent of a deck of cards,” he said.

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Guidelines

In Morgan County, the following waterways have contaminated fish and ADPH recommends that consumption should be limited as indicated:

• Baker’s Creek; all species; PFOS; do not eat any.

• Flint Creek downstream of the West Flint Creek confluence near U.S. 31; largemouth bass; mercury; do not eat any.

• Flint Creek embayment at Wheeler Reservoir beginning 1 mile downstream of Alabama 67; largemouth bass; mercury; two meals per month.

• Wheeler Reservoir south of main river channel from river miles 303 to 296; PFOS; largemouth bass; one meal per month.

In Lawrence County, the following waterways have contaminated fish and consumption should be limited as indicated:

• Big Nance Creek at County Road 25; mercury; two meals per month of golden redhorse and do not eat any largemouth bass.

• Big Nance Creek embayment upstream of Alabama 101 bridge; mercury; one meal per month of catfish and two meals per month of largemouth bass.

• Fox Creek embayment of Wheeler Reservoir; mercury and PFOS; largemouth bass; one meal per month.

In Limestone County, the following waterways have contaminated fish and consumption should be limited as indicated:

• Limestone Creek embayment beginning 1 mile upstream of confluence with Tennessee River; mercury; largemouth bass; two meals per month.

• Round Island Creek at Wheeler Reservoir and extending 1.5 miles upstream; mercury; largemouth bass; do not eat any.

• Wheeler Reservoir near river mile 296; PFOS; largemouth bass; one meal per month.

Guarisco said mercury in fish is a “global contaminant” not limited to north Alabama, but said the more forested land in an area and the more rain an area receives, the greater the potential for mercury contamination in nearby waters.

“Mercury can enter the atmosphere as very fine particulates down to dust, get caught up in the atmosphere aloft and transport around the globe,” Guarisco said. “When you get mercury depositing on leaves, the leaves eventually fall off the trees, they join the litter on the forest floor and when a rain event comes, it pushes all that material into your local water body.”

Guarisco said largemouth bass appear frequently on the list of advisories as they often eat other contaminated fish.

“Basically, the largemouth bass diet consists primarily of other fish, so they transfer that body of mercury every time they (eat),” he said. “They are plentiful and are widely distributed across the United States, so it makes a convenient database between states that have largemouth bass in the population.”

Mercury contamination isn’t a barrier to recreational fishing, ADPH said.

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Call for more testing

David Whiteside, executive director of nonprofit Tennessee Riverkeeper, said people should stick to catch-and-release fishing with bigger fish.

“We are seeing a correlation with fish at the top of the food chain having higher mercury levels, and I would think that the fish that are the biggest, fattest specimen of their species have eaten a lot of fish,” Whiteside said. “It’s probably best to play it safe and avoid those fish.”

This year’s advisories in Morgan, Lawrence and Limestone counties are identical to those issued last year, but Whiteside said he would like to see the state test contaminant levels more frequently.

“We have an abundance of creeks and rivers and fish, and we also have an abundance of people that go and catch those fish and eat them,” Whiteside said. “We encourage the state to increase their testing of these fish and at least do it at different times of the year, because we know Alabamians are not just out there one season catching and eating.”

ADPH issues its advisories based on data from testing performed once yearly in the fall by the Alabama Department of Environmental Management. Guarisco said this is because of greater fat content in fish at that time.

“You’re looking for fish that have built up a pretty good layer of fat in them so you can get an indication of any kind of contamination,” he said.

Guarisco said ADPH is “not exactly sure” if there could be higher mercury levels in other seasons and that this is something only the Department of Environmental Management could determine with additional testing. He said fish advisories are generally only changed if a local incident like an oil spill occurs.

Additionally, Whiteside said ADPH is lagging behind by releasing its advisory information in July by the time which fishing has already taken place across the state for several months.

The last time advisories were released earlier was in 2018 when the bulletin was distributed in May, but the largest bass in the state are generally caught between February and April, according to the Alabama Department of Conservation and Natural Resources.

“Unfortunately, we got behind, and it’s my intent to get it out earlier than July,” Guarisco said. “COVID has kind of put the crimp on a lot of things (and) … did not help putting out the fish advisories any earlier.”