Guntersville Reservoir

Ecological health rating

The ecological health condition of Guntersville Reservoir rated good in 2009. Guntersville’s ecological health scores have fluctuated within the good range all years except 2008, when it rated fair. This was largely because several ecological indicators at the forebay (dissolved oxygen, chlorophyll, and bottom life) received their lowest scores to date, which likely resulted from the low flow conditions.

Ecological health scores tend to be lower in most Tennessee River reservoirs during years with lower flows because chlorophyll concentrations are typically higher and dissolved oxygen levels are lower. In turn, the low dissolved oxygen can negatively affect bottom life.

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

Guntersville Reservoir Ecological Health Ratings, 1994-2009

Click chart for raw data.

The table below shows the ratings for individual ecological health indicators at Guntersville in 2009. These ratings are briefly explained in the paragraphs that follow.

Monitoring locations	Dissolved oxygen	Chlorophyll	Fish	Bottom life	Sediment
Ecological Health Indicators for Guntersville Reservoir, 2009
Forebay	Good	Poor	Fair	Fair	Good
Mid-reservoir	Good	Good	Fair	Fair	Good
Inflow			Fair	Good
Dissolved oxygen Dissolved oxygen rated good at both the forebay and mid-reservoir monitoring locations. Dissolved oxygen conditions typically rate good in Guntersville Reservoir. However, the forebay received its first fair rating in 2008, rating at the upper end of the fair range. This was because concentrations were low in a small area along the bottom of the reservoir in early summer. Chlorophyll Chlorophyll rated poor at the forebay and good at the mid-reservoir monitoring location. Chlorophyll concentrations were elevated at the forebay during several sample periods Chlorophyll ratings have fluctuated between good, fair, and poor at the forebay, generally in response to reservoir flows. Chlorophyll concentrations at the mid-reservoir monitoring location have consistently rated good. Fish As in previous years, low catch rates contributed to fair ratings for the fish community at all locations. While the fish assemblage generally rates fair at the forebay and mid-reservoir, ratings at the inflow have fluctuated between good and fair and even poor in 2000 (one point from fair), the lowest score to date for the reservoir. This fish rating rebounded to good in 2002 and to a “high fair” in 2004, possibly indicating that the poor rating was an anomaly. Bottom life Bottom life rated fair at the forebay and mid-reservoir and good at the inflow. Bottom life typically rates fair or good at all monitoring locations. However, bottom life at the forebay received its lowest rating, at the low end of the fair range, in 2008. The forebay’s fair rating in 2009 represented some improvement in density and diversity of organisms in the samples collected from the reservoir bottom as compared with 2008. Sediment Sediment quality rated good at both the forebay and mid-reservoir monitoring locations because no PCBs or pesticides were detected, and no metals had elevated concentrations. Sediment quality typically rates fair at the forebay due to the presence of one or more contaminants: PCBs, chlordane, or zinc. The sediment rating at the mid-reservoir has fluctuated between good and fair due primarily to chlordane, which was detected in 1996, 2002, and 2004; PCBs were detected at this location in 2002. See definitions of ecological health indicators and monitoring locations.

Fish consumption advisories

Guntersville 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 Cedar Creek Reservoir, visit the Epidemiology Division of Alabama Department of Public Health’s web page. http://www.adph.org/tox/index.asp?ID=1360