Melton Hill Reservoir
The overall ecological condition of Melton Hill rated fair in 2012. Melton Hill received a good rating in 2006 and 2010 but rated fair in all other years monitored. The higher ecological health scores were primarily due to two indicators — chlorophyll and bottom life — rating near the upper end of their historic ranges.
TVA monitors three locations on Melton Hill Reservoir — the deep, still water near the dam, called the forebay; the middle part of the reservoir; and the riverlike area at the upper end of the reservoir, called the inflow. Monitoring is usually done on a two-year cycle.
Ecological Health Indicators for Melton Hill Reservoir, 2012
Dissolved oxygen rated poor at the forebay and good at the mid-reservoir location. A large portion of the lower water column at the forebay had low dissolved oxygen concentrations in June, resulting in a poor rating. Dissolved oxygen has rated good at the mid-reservoir location all years monitored and typically has rated good in the forebay unless there was an extended period with low flow. Low flow conditions can allow water to sit long enough that oxygen in the lower water column becomes depleted as it is used in the natural process of decomposition. This was the case in 2012 and in 2000, 2001 and 2008 when dissolved oxygen rated fair at the forebay location.
Chlorophyll rated fair at the forebay and good at the mid-reservoir monitoring location. Annual average chlorophyll concentrations have fluctuated through time at the mid-reservoir, with no specific trend of increasing or decreasing. Chlorophyll concentrations have shown an overall trend of increasing at the forebay since monitoring began in 1991. Chlorophyll rated good at the forebay during the 1991 to 1996 time period. Since 1998, chlorophyll ratings have fluctuated between fair and poor at this location. Reservoir flows have played a part in the year-to-year fluctuations as low-flow conditions tend to allow more time for algal populations to become established.
The fish community rated good at the forebay, fair at the mid-reservoir and poor at the inflow. Consistent with previous years, the fish assemblage at each monitoring location was characterized by lower numbers of fish and higher proportions of tolerant individuals than expected. As in most years, improved diversity at the mid-reservoir and forebay, respectively, resulted in higher ratings at these locations.
Bottom life rated fair at the forebay and mid-reservoir locations and poor at the inflow. Scores for bottom life have fluctuated within the “low fair” to poor range at the forebay and within the poor range at the inflow location. Scores have improved, however, at the mid-reservoir location since 1994 with scores shifting from the low end of the fair range to the middle of the fair range and even rating good in 2006. The improved ratings were primarily due to an increase in the number of organisms less tolerant of poor conditions.
Sediment quality rated fair at the forebay because samples contained slightly more arsenic than would be expected to occur naturally. The mid-reservoir location rated good because no PCBs or pesticides were detected, and no metals had elevated concentrations. Arsenic, chlordane, copper and PCBs have exceeded suggested limits in some previous years.
Fish consumption advisories
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, Tennessee Wildlife Resource Agency.