The Tennessee Department of Environment and Conservation (TDEC) today announced the expansion of the existing precautionary fish consumption advisory for bass species in the Little River in Blount County in East Tennessee. The pollutant of concern is mercury.
The Little River advisory previously issued in June of 2019 was for a portion of the Little River within the Great Smoky Mountains National Park. The impacted segment was identified as extending from the national park boundary upstream of Townsend near river mile 35 upstream to the area called “The Sinks” near mile 41.5. Today’s action extends the advisory downstream from the national park boundary down to the U.S. Highway 129 bridge near Maryville. While the previous advisory was for smallmouth bass only, that was because that was the only species of black bass likely to be found within the national park.
TDEC advises that pregnant or nursing mothers and children avoid eating any black bass from the Little River. All others should limit consumption of bass to one meal per month. Other recreational activities on this river such as rafting, inner-tubing, kayaking, swimming, wading, and catch-and-release fishing carry no risk from mercury. There is no advisory on trout, which were found to have generally low levels of mercury in previous surveys.
“We provide these advisories so people can make informed decisions about whether or not to consume fish they catch,”TDEC Deputy Commissioner Greg Young said.
“Precautionary fish consumption advisories are directed to sensitive populations such as children, pregnant women, nursing mothers and those who may eat fish frequently from the same body of water.”
The information that led to the expansion of the advisory was the result of cooperative fish tissue sampling by the Tennessee Wildlife Resources Agency (TWRA) and the department. Fish were captured during the summer of 2019 with the goal of determining how far downstream from the national park the elevated levels of mercury in bass extended. Fish were collected from Townsend downstream to Maryville and documented mercury levels well above the trigger currently used by the department. This trigger, 0.3 mg/kg (parts per million), was jointly recommended by both the U.S. Environmental Protection Agency and U.S. Food and Drug Administration.
TDEC considers the source of mercury in the Little River to be atmospheric deposition. According to the EPA, atmospheric deposition due to the global burning of coal is the most frequent reason for elevated levels of mercury in fish. TDEC will post warning signs at public access points and will work with the Tennessee Wildlife Resources Agency to communicate this information to the public.
The Tennessee Water Quality Control Act identifies the commissioner of the Department of Environment and Conservation as having the authority and responsibility to issue advisories for either water contact hazards like pathogens or excessive health risks due to the accumulation of contaminants in fish or shellfish. Tennessee’s General Water Quality Criteria provide additional guidance regarding the conditions under which advisories may be warranted.
There are two types of fish consumption advisories issued by TDEC based on the levels of contaminants present in fish tissue. “Do not consume” fishing advisories are issued when levels of contaminants in fish tissue would represent a threat to the general population. Precautionary advisories are issued when contaminant levels are lower, but would still pose a risk to sensitive populations.
According to the U.S. Environmental Protection Agency, mercury is a naturally occurring element that can be found throughout the environment. Human activities such as burning coal, some industrial processes and waste incineration have caused the amount of mercury in some areas to increase. The primary way people in the U.S. are exposed to mercury is by eating fish containing methylmercury, a toxic form of mercury that accumulates easily in organisms.
Where new advisories have been issued, TDEC will immediately begin the process of putting up signs at primary public access points. TDEC works in partnership with the Tennessee Wildlife Resources Agency to communicate information about fishing advisories.
For a complete listing of Tennessee’s current fishing advisories plus additional information about the advisory issuance process, visit https://www.tn.gov/content/dam/tn/environment/water/planning-and-standards/wr_wq_fish-advisories.pdf.
An EPA website has additional information about mercury at https://www.epa.gov/fish-tech/epa-fda-advice-about-eating-fish-and-shellfish.