Chatuge Reservoir

Ecological health rating

Chatuge Reservoir rated fair in 2007, primarily due to lower average chlorophyll concentrations. It also rated fair in 2001 due to improved chlorophyll and dissolved oxygen conditions. In eight out of the past 10 years, however, Chatuge has rated poor.

Weather conditions—particularly, the timing and amount of rainfall—and the related changes in runoff have proved to be major factors in the variation of ecological health scores for Chatuge and many other reservoirs. Dissolved oxygen and chlorophyll—the indicators most responsive to changes in weather conditions—tend to rate better in the forebay area of tributary reservoirs with long residence times (reservoirs in which the water sits for a longer period) during drought conditions and to rate lower during periods of more normal to high rainfall and runoff. This is because fewer nutrients and less organic material are washed into the reservoir when rainfall and runoff are low, which tends to result in lower chlorophyll concentrations and less oxygen demand to decompose organic materials.

TVA has monitored two locations on Chatuge Reservoir—the deep, still water near the dam and the Shooting Creek location—annually since 1998.

Chatuge Reservoir Ecological Health Ratings, 1994-2007

Click chart for raw data.

The table below shows the ratings for individual ecological health indicators at Chatuge in 2006. These ratings are briefly explained in the paragraphs that follow.

Monitoring locations	Dissolved oxygen	Chlorophyll	Fish	Bottom life	Sediment
Ecological Health Indicators at Chatuge Reservoir, 2007
Forebay	Poor	Good	Fair	Fair	Good
Shooting Creek	Poor	Good	Fair	Poor	Poor
Dissolved oxygen Dissolved oxygen rated poor at both monitoring locations due to low concentrations in the lower water column from August through October. Ratings have fluctuated between fair and poor in response to the timing and amount of rainfall. Chlorophyll Chlorophyll rated good at both monitoring locations. Similar to dissolved oxygen, chlorophyll ratings have fluctuated between good, fair, and poor in response to the timing and amount of rainfall. However, average chlorophyll concentrations have shown a trend of increasing at both locations since TVA began monitoring Chatuge Reservoir in the early 1990s. Fish The fish community rated fair at both monitoring locations—the same as in most previous years. Catch rates were lower than expected, and species diversity was fair. Bottom life Bottom life rated at the low end of the fair range at the forebay and poor at the Shooting Creek location. Bottom life has rated fair or poor each year because relatively few organisms are found in samples collected from the reservoir bottom, and most are species able to tolerate poor conditions. Sediment Sediment quality rated good at the forebay because no pesticides or PCBs were detected, and concentrations of metals were within expected background levels. The Shooting Creek location rated poor due to elevated concentrations of chromium, copper, and nickel. Elevated concentrations of one or more of these metals are usually detected in the sediments of Chatuge. See definitions of ecological health indicators and monitoring locations.

Fish consumption advisories

The state of Georgia issued a fish consumption advisory for spotted bass in the Georgia portion of Chatuge Reservoir because of mercury contamination. The state advises people not to eat more than one meal a week of spotted bass between 12 and 16 inches in length.

TVA collected channel catfish and largemouth bass from the reservoir for tissue analysis in the autumn of 2004. The results, which were provided to state agencies in Georgia and North Carolina, were similar to those of previous years. TVA will collect fish from Chatuge again in the autumn of 2008.