The overall ecological condition of Melton Hill Reservoir rated at the upper end of the “fair” range in 2018. Melton Hill has rated “fair” most years. Higher ratings (“good”) in 2006, 2010, and 2016 were primarily due to two indicators — chlorophyll and bottom life — scoring near the upper end of their historic ranges. In 2016, however, fish community scores were also at the upper end of their historic ranges, which contributed to the reservoir’s higher overall score.
The ecological health of Melton Hill Reservoir has been assessed using the same methodology since 1994. Ecological health evaluations focus on five indicators: dissolved oxygen, chlorophyll, sediment quality, benthic macroinvertebrate community (bottom life), and the fish assemblage. TVA monitors three locations on Melton Hill Reservoir — the deep, still water near the dam, called the forebay (Clinch River Mile 24.0); the middle part of the reservoir (Clinch River Mile 45.0); and the riverlike area at the upper end of the reservoir, called the inflow (Clinch River Mile 59.0). Only bottom life and the fish assemblage are assessed at the inflow monitoring location.
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>72 = Good
59-72 = Fair
<59 = Poor
Dissolved oxygen in 2018 rated “good” at the two locations where this indicator is monitored. Dissolved oxygen has rated “good” at the mid-reservoir location all years monitored and typically has rated “good” at the forebay unless there was an extended dry period, which reduced flows through the reservoir. Low flow conditions can allow water to sit long enough that oxygen in the deeper waters becomes depleted as it is used in the natural process of decomposition. This was the case in 2012 when dissolved oxygen rated “poor” at the forebay, and in 2000, 2008, and 2014 when dissolved oxygen rated “fair” at this location. Prevailing weather patterns and the related changes in both reservoir flows and the influxes of nutrients and organic matter are major factors in differing dissolved oxygen conditions from year-to-year.
Chlorophyll in 2018 rated “fair” at the forebay and “good” at the mid-reservoir. Chlorophyll has rated “good” or high “fair” at the mid-reservoir each year monitored. Chlorophyll at the forebay generally rates “fair”, but it has also been assessed “good” and “poor” ratings some years. As with dissolved oxygen, prevailing weather patterns have played a part in the year-to-year fluctuations.
In 2018, the fish community was assessed a “fair” rating at the mid-reservoir and inflow and a “good” rating at the forebay. Historically, fish community ratings at the forebay and mid-reservoir have fluctuated between “good” and “fair”, while ratings at the inflow have fluctuated between “fair” and “poor”. The lower ratings at the inflow are due, at least in part, to the cold water released from the lower depths of Norris Reservoir upstream.
In 2018, the number and variety of fish observed at each location were consistent with previous years. A total of forty-seven species was observed reservoir-wide. Some of the more interesting species included muskellunge, which continue to thrive in Melton Hill Reservoir, and western blacknose dace and snubnose darters.
Bottom life in 2018 rated “poor” at the forebay and inflow monitoring locations and “fair” at the mid-reservoir. Bottom life generally rates a low “fair” or “poor” at the forebay and “poor” at the inflow location. Limited varieties of organisms typically are collected at these locations, and those collected are primarily species able to tolerate a wide variety of environmental conditions. Bottom life at the mid-reservoir generally rates “fair” due to greater abundance and diversity, which includes a better representation of sensitive and long-lived species such as mayflies and snails.
Sediment quality in 2018 rated “good” at the two locations where this indicator is monitored: the forebay and mid-reservoir. No PCBs or pesticides were detected and concentrations of metals were within suggested background levels.
Concentrations of arsenic, copper, chlordane and PCBs have resulted in lower sediment quality ratings in some previous years. Chlordane and PCBs have been detected at low concentrations, but they are man-made compounds and do not occur naturally. The pesticide chlordane was banned from use in the 1980s. PCBs were banned from commercial production in 1979, though they may be present in products and materials produced before the ban. These compounds continue to be detected sporadically in sediments because of their persistence in the environment. Similarly, the State of Tennessee advises that catfish from Melton Hill Reservoir should not be eaten due to contamination with PCBs. PCB concentrations in catfish have, however, exhibited a decreasing trend over the Ecological Health monitoring period.
The metals (arsenic and copper) naturally occur in soils but can also originate from many sources. Their concentrations in sediments deposited in the reservoir are generally near—slightly above or slightly below—suggested background concentrations.
TVA maintains a program to examine contaminants in fish fillets from TVA reservoirs and their major tributary streams on a rotational basis. The data collected from this program is distributed to the state officials who are responsible for placing or removing fish tissue consumption advisories on those bodies of water. For information on advisories currently in effect for Melton Hill Reservoir, visit the Tennessee Wildlife Resources Agency.