Melton Hill Reservoir

Ecological health rating

The overall ecological condition of Melton Hill rated fair in 2008. Melton Hill received a good rating in 2006 but rated fair in all previous years monitored. The higher score in 2006 was due to several indicators rating at the upper end of their historic range and to an improvement in bottom life at the mid-reservoir location.

Since monitoring began in 1991, higher chlorophyll concentrations and improved sediment ratings have been observed. The presence of a greater area of water with low dissolved oxygen during 2000 and 2001 was again observed during 2008. These observations are discussed below.

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.

Melton Hill Reservoir Ecological Health Ratings, 1994-2008

Click chart for raw data.

The table below shows the ratings for individual ecological health indicators at Melton Hill in 2008. These ratings are briefly explained in the paragraphs that follow.

Monitoring locations	Dissolved oxygen	Chlorophyll	Fish	Bottom life	Sediment
Ecological Health Indicators for Melton Hill Reservoir, 2008
Forebay	Fair	Fair	Fair	Poor	Good
Mid-reservoir	Good	Fair	Fair	Fair	Good
Inflow			Fair	Poor
Dissolved oxygen Dissolved oxygen rated fair at the forebay and good at the mid-reservoir location. Dissolved oxygen typically rates good in Melton Hill Reservoir during years with higher flows. The fair rating at the forebay was the result of drought conditions which began in 2007, one of the driest years on record, and continued into 2008. Conditions were similar in 2000 as well as in 2001, an off year when not all ecological indicators were monitored. During those years, a greater area of water with low dissolved oxygen was present at the forebay due to low reservoir flows, resulting in fair ratings. Drought conditions that began in summer 1998 and continued into 2002 produced near-record low flows in the Tennessee Valley. Low flows allowed the water to sit long enough that oxygen in the lower water column became depleted as it was used in the natural process of decomposition. Flows were below average for Melton Hill in 2002, but were apparently sufficient to prevent oxygen depletion in the lower water column. Chlorophyll Chlorophyll rated fair at both monitoring locations. Average annual chlorophyll concentrations have shown an overall trend of increasing at both locations since monitoring began in 1991. Chlorophyll rated good at both locations during the 1991 to 1996 time period. Since 1998, chlorophyll ratings have fluctuated between fair and poor at the forebay and good, fair, and poor at the mid-reservoir 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, but there remains an overall trend of increasing concentrations. Fish The fish community rated fair at all three monitoring locations. Historically, the fish community has rated good or fair at the forebay, fair all years at the mid-reservoir location, and fair or poor at the inflow monitoring location. Bottom life Bottom life rated poor at the forebay and poor at the inflow monitoring locations and fair at the mid-reservoir location, similar to most previous years. Most of the organisms found in samples collected from the reservoir bottom were species able to tolerate poor conditions. Sediment Sediment quality rated good at both monitoring locations because no PCBs or pesticides were detected, and no metals had elevated concentrations. Low levels of chlordane, a pesticide previously used to control termites and crop pests, were frequently detected in sediment samples from both sites in past years. Arsenic, PCBs, and copper also have exceeded suggested limits in past years. See definitions of ecological health indicators and monitoring locations.

Fish consumption advisories

The state of Tennessee has issued a fish consumption advisory against eating catfish from Melton Hill Reservoir because of PCB contamination. TVA collected channel catfish and largemouth bass from the reservoir for tissue analysis in the autumn of 2006. The results, which were similar to those of previous years, will be provided to state agencies in Tennessee. TVA plans to analyze fish from the reservoir again in autumn 2008.