Possible mercury in local-caught fish, according to state -- consumption by pregnant women or children should be limited.
The Tennessee Department of Environment and Conservation (TDEC) announced Jan. 13 a precautionary fish consumption advisory due to mercury on Normandy Reservoir on the Duck River in Bedford and Coffee counties.
In a 2006 statewide screening of Tennessee rivers and lakes, Normandy Reservoir was identified as a waterbody where mercury levels in fish were elevated, but not over the trigger used to issue advisories. Today’s action, which is the result of additional studies by TDEC and the Tennessee Valley Authority, is for black bass species in the entirety of the reservoir.
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 frequently from the same body of water.”
The Tennessee Valley Authority (TVA) collected fish in Normandy Reservoir in 2010, 2011, 2013, and 2016. TVA’s fish tissue monitoring station is located at river mile 249.5 in the lake forebay near the dam.
In 2012 and 2013, the department collected fish at the forebay station and in 2013, additionally sampled at the Manchester/Tullahoma water intake at mile 255.1.
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.
TDEC considers the source of mercury in Normandy Reservoir 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.