tva logoTennessee Valley Authority

Nickajack Reservoir

Ecological health rating

As in previous years, Nickajack Reservoir rated good in 2011. The ecological health score for Nickajack has consistently been among the highest of all the reservoirs monitored by TVA. Nickajack is a small, narrow reservoir with a short retention time. It usually takes only three or four days for water to flow through the reservoir, which helps keep the water mixed, preventing it from stratifying (separating into layers of different temperatures) during the summer. This allows oxygen in the lower water column to be replenished and limits algal growth, thereby reducing chlorophyll concentrations.

TVA monitors two locations on Nickajack Reservoir—the deep, still water near the dam, called the forebay, and the riverlike area at the extreme upper end of the reservoir, called the inflow—usually on a two-year cycle.

Nickajack Reservoir Ecological Health Ratings, 1994-2011

rating chart

Click chart for raw data.  

 

The table below shows the ratings for individual ecological health indicators at Nickajack in 2011. These ratings are briefly explained in the paragraphs that follow.

Ecological Health Indicators at
Nickajack Reservoir, 2011

Monitoring
locations

Dissolved oxygen

Chlorophyll

Fish

Bottom life

Sediment
Forebay
Inflow      

Dissolved oxygen

As in previous years, dissolved oxygen rated good at the forebay.

Chlorophyll

Chlorophyll rated good . Chlorophyll has rated good in all years except 2007.  The extremely dry conditions and resultant low flows through the reservoir in 2007 allowed more time for algae to grow, resulting in a poor rating.

Fish

The fish community rated fair at both monitoring locations. Consistent with previous years, fewer fish and fish species were collected at the forebay than expected, and a greater proportion of those were tolerant individuals. At the inflow, the fish community scored one point below the good range. A good number and variety of fish were collected, but this site also had a greater proportion of tolerant individuals, resulting in a lower rating. The fish community has rated good at the inflow in all previous years.

Bottom life

Bottom life rated fair at the forebay and good at the inflow location. Bottom life rated good at both monitoring locations all previous years except 2007, when it rated ”high fair” at the forebay. Typically a “good” variety of organisms are found, including long-lived and sensitive organisms—such as snails and mayflies—which are indicative of good water quality and conditions that allow for long-term survival.

Sediment

Sediment quality rated fair due to low levels of PCBs.  No pesticides were detected, and concentrations of metals were within the expected background levels. Low levels of PCBs have been detected in samples in past years, and chlordane was detected in 1993.

 

See definitions of ecological health indicators and monitoring locations.

 

Fish consumption advisories

Nickajack Reservoir - 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 Nickajack Reservoir, visit the Water Quality Division of Tennessee Department of Environment & Conservation’s web page. http://www.tn.gov/environment/water.shtml

 

 

 

map to apalachia

Nickajack Reservoir is located on the Tennessee River below Chattanooga in southeastern Tennessee.

 

More about Nickajack

Sport fishing ratings

Spring sportfish survey results

General information

To see monitoring results for other TVA reservoirs, choose from the list below.

 

 

           
Content for id "future1" Goes Here
Content for id "future2" Goes Here
Content for id "future3" Goes Here