Nottely
Reservoir
Ecological
health rating
The ecological health of Nottely Reservoir rated poor in 2007. Nottely typically rates poor due to low ratings for dissolved oxygen, chlorophyll, and bottom life. Ratings for these indicators improved in 2001, rating at the upper end of their historic range and resulting in a higher overall health rating of fair. However, subsequent monitoring indicates that the improvements were only a temporary result of the unusual rainfall and reservoir flow patterns in 2001.
TVA monitors two locations on Nottely Reservoir—the deep, still water near the dam, called the forebay, and the middle part of the reservoir—usually on a two-year cycle.
Nottely
Reservoir Ecological Health Ratings, 1994-2007
Click chart for raw
data.
The table below
shows the ratings for individual ecological health indicators at Nottely
in 2007. These ratings are briefly explained in the paragraphs that follow.
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Ecological
Health Indicators at
Nottely Reservoir, 2007
|
|
Monitoring
locations
|
Dissolved
oxygen
|
Chlorophyll
|
Fish
|
Bottom
life
|
Sediment
|
| Forebay |
|
|
|
|
|
| Mid-reservoir |
|
|
|
|
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Dissolved oxygen
Dissolved oxygen rated poor at both the forebay and mid-reservoir monitoring locations. A large proportion of the water column contained low dissolved oxygen concentrations during mid-to- late summer at these locations. This is similar to all previous years, except 2001 when oxygen concentrations were significantly higher at the forebay and rated good, and 2005 when significant rain events in late summer helped replenish oxygen in the upper reaches of the reservoir, resulting in a fair rating at the mid-reservoir location. Although dissolved oxygen typically rates poor at both locations, the extent and duration of low dissolved oxygen has varied in response to the timing and amount of rainfall.
Chlorophyll
Average summer chlorophyll concentrations were elevated at both monitoring locations, rating poor. A poor rating is typical at the mid-reservoir location, but ratings at the forebay have varied from good to fair to poor. As with dissolved oxygen, chlorophyll concentrations have varied in response to the timing and amount of rainfall. However, average chlorophyll concentrations have shown a general trend of increasing at the mid-reservoir location since TVA began monitoring Nottely in the early 1990s.
Fish
As in previous years, the fish community rated fair at both monitoring locations. The condition of the fish community continues to rate fair, rather than good, because of reduced species diversity and density.
Bottom life
Bottom life rated poor at the forebay because of the low density and diversity of organisms collected. This indicator rated at the low end of the fair range at the mid-reservoir location where higher densities of animals were found. Bottom organisms at both locations were predominantly those tolerant of poor conditions.
Sediment
Sediment quality rated good at both locations. No pesticides or PCBs were detected, and concentrations of metals were within expected background levels. A good rating is typical, although sediment quality rated fair in 1995 because low levels of DDE were detected. DDE is a breakdown product of DDT. DDT entered the environment when it was used as a pesticide.
See definitions of
ecological health indicators and monitoring locations. |
|
Fish
consumption advisories
There are two fish
consumption advisories in effect at Nottely Reservoir. The state
of Georgia advises against eating more than one meal per week of
largemouth
bass greater than 12 inches or striped bass greater than 16 inches because
of mercury contamination.
TVA collected channel catfish and largemouth bass from Nottely for tissue analysis in the autumn of 2005. The results, which will be provided to state agencies, were similar to those of previous years. TVA will analyze fish from Nottely again in the autumn of 2009.
Tennessee Valley Authority
