Tims Ford Reservoir
The ecological health of Tims Ford Reservoir rated “poor” in 2022, similar to previous years. Low dissolved oxygen concentrations in the lower water column and “poor” ratings for bottom life continue to drive the lower ratings in Tims Ford. “Fair” ratings for chlorophyll and sediment quality have also reduced the overall ecological health score in some years.
The ecological health of Tims Ford Reservoir has been monitored using the same methodology since 1994. Ecological health evaluations focus on five indicators: dissolved oxygen, chlorophyll, sediment quality, benthic macroinvertebrate community (bottom life), and the fish assemblage. TVA monitors two locations on Tims Ford Reservoir — the deep, still water near the dam, called the forebay (Elk River Mile 135.0), and the middle part of the reservoir (Elk River Mile 150.0).
Tims Ford Reservoir Ecological Health Ratings, 1994-2022
To view or export the data, click on the menu in the top-right corner of the chart.
>72 = Good
59-72 = Fair
<59 = Poor
Ecological Health Indicators for Tims Ford Reservoir - 2022
Monitoring location | Dissolved oxygen | Chlorophyll | Fish | Bottom life | Sediment |
---|---|---|---|---|---|
Forebay | Poor | Good | Good | Poor | Fair |
Mid-reservoir | Poor | Good | Good | Poor | Fair |
Dissolved oxygen
Dissolved oxygen rated “poor” at both monitoring locations in 2022, consistent with findings from previous years. Oxygen concentrations were low (<2 mg/L) in portions of the lower water column during summer and autumn at both monitoring locations, including extended periods of time when an area of water was completely devoid of oxygen.
As part of TVA’s Reservoir Release Improvement Program, TVA has installed aeration equipment at Tims Ford Dam to improve the quality of water in the Elk River downstream from the dam. Learn more about these improvements.
Chlorophyll
In 2022, chlorophyll rated “good” at both monitoring locations. At the forebay, chlorophyll has rated “good” or high “fair” each year monitored, but ratings at the mid-reservoir have fluctuated more, varying between “good”, “fair”, and “poor”. Chlorophyll concentrations have varied in response to the timing and amount of rainfall. Because of the mid-reservoir’s proximity to the Elk River inflow, chlorophyll concentrations at this location are more influenced by the nutrients flowing into the reservoir.
Fish
The fish community in 2022 rated “good” at both monitoring locations. Historically, the fish community has been assessed “good” or high “fair” ratings. In 2022, a total of twenty-eight fish species was observed, including “good” numbers of sunfish, intolerant species (species known to require good water quality conditions), and top carnivores (e.g., black bass, walleye, and yellow bass). Fish health also was assessed a “good” rating with low incidences of disease and parasites.
Bottom life
As in previous years, bottom life rated “poor” at both monitoring locations because few benthic invertebrates were collected, and all were species capable of tolerating a wide variety of environmental conditions. Low dissolved oxygen concentrations and cold water temperatures in the lower water column are contributing factors.
Sediment
Sediment quality rated “fair” for both monitoring locations in 2022. Nickel and arsenic exceeded suggested background levels in both the forebay and mid-reservoir samples. Sediment quality typically rates “fair” at the forebay and “good” or “fair” at the mid-reservoir location. Nickel and arsenic have exceeded suggested background levels at both locations in some previous years. Low levels of the pesticide chlordane have been detected at the mid-reservoir location in the past (1996, 1998, and 2002). Additionally, low levels of PCBs were detected in the samples at both monitoring locations in 2016 and 2019.
Fish consumption advisories
TVA maintains a program to examine contaminants in fillets of fish collected from TVA reservoirs and their major tributary streams on a rotational basis. The data collected from this program are 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 Tims Ford Reservoir, visit the Tennessee Department of Environment and Conservation web page.