The Tennessee Department of Environment and Conservation (TDEC) on Thursday announced the extension of the existing precautionary fish consumption advisory on the Nolichucky River due to mercury.
In August 2018, TDEC issued a precautionary advisory for smallmouth bass and channel catfish in the Nolichucky River from Douglas Reservoir upstream to the mouth of Bent Creek at river mile 14.9. At that time, the department pledged to collect additional data to determine if the elevated mercury levels extended any further upstream.
Today’s action, which is the result of these additional studies, expands the advisory to include all black bass species and extends it so that the entire length of the Nolichucky River in Tennessee is included, from Douglas Reservoir to the North Carolina state line. The existing advisory for channel catfish in the downstream portion of the Nolichucky River is not being changed.
TDEC advises that pregnant or nursing mothers and children avoid eating the fish species included in the advisory and that all others limit consumption to one meal per month. Other recreational activities such as boating, swimming, wading, and catch-and-release fishing carry no risk.
“We provide these advisories so the community can make informed decisions about whether or not to consume the fish they catch,” TDEC Deputy Commissioner Greg Young said. “Unlike ‘do not consume’ advisories that warn the general population to avoid eating fish from a particular body of water altogether, precautionary fish consumption advisories are specifically directed to sensitive populations such as children, pregnant women, nursing mothers and those who may eat fish very frequently from the same body of water.”
As a follow up to the August 2018 advisory, the department collected additional fish in the Tennessee portion of the Nolichucky River in the fall of 2018, plus the spring and summer of 2019. Specifically, fish were collected at river mile 8.5 (Hurley Island), at mile 20.9 (u/s of Conway Bridge), at mile 68 (Davy Crockett Birthplace State Park), and at mile 83.9 (off Charlie Carson Road). Attempts to capture bass near the North Carolina state line were unsuccessful, but they are documented in historical surveys to be present.
These studies documented that in black bass species – which include smallmouth, largemouth and spotted bass – mercury levels were 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. Although targeted for collection, few data are available for walleye, a popular target for fishermen, and the results were inconclusive. Walleye are not included in the advisory. Additionally, channel catfish in the upper parts of the Nolichucky had mercury levels below the trigger.
TDEC considers the source of mercury in the Nolichucky 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.
About Fish Consumption Advisories
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 subpopulations such as children, pregnant women, nursing mothers and those who eat fish frequently from the same body of water.
According to the U.S. Environmental Protection Agency, mercury is a naturally occurring element that can be found throughout the environment. Human activities have caused the amount of mercury in some areas to increase. The primary way people in the United States 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, visithttps://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.