The overall ecological health of Tellico Reservoir rated “fair” in 2021. Tellico has rated either “poor” or at the low end of the “fair” range all years except 1994, when it scored slightly higher due primarily to improved chlorophyll concentrations.
The ecological health of Tellico 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 fish assemblage. TVA monitors two locations on Tellico Reservoir — the deep, still water near the dam, called the forebay (Little Tennessee River Mile (LTRM) 1.0); and the middle part of the reservoir (LTRM 15.0) — usually on a two-year cycle.
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
*Sediment quality was assessed based on monitoring results from 1994 through 2019.
Dissolved oxygen rated “fair” at the forebay and “good” at the mid-reservoir. Historically, dissolved oxygen ratings at the forebay have fluctuated between “good”, “fair”, and “poor”. This indicator has rated “good” at the mid-reservoir all other years monitored except 2006 and 2017, when it rated “high fair”. Low dissolved oxygen concentrations have occurred at the mid-reservoir location in several other years, but only for short durations, and the total area of the water column affected remained small enough that conditions rated “good”. Prevailing weather patterns and the related changes in reservoir flows are major factors in differing dissolved oxygen conditions from year-to-year. Poorer dissolved oxygen conditions typically occur as a result of reduced flows through the reservoir during periods of low rainfall and runoff.
Chlorophyll rated “fair” at both monitoring locations in 2021. Higher chlorophyll concentrations can be expected at the forebay because of the exchange of water from the nutrient-rich forebay of Fort Loudoun Reservoir via the canal connecting the two reservoirs. However, concentrations were slightly higher than expected at the mid-reservoir given the nutrient-poor soils in the upstream watershed. Chlorophyll typically rates “poor” at the forebay and “fair” or “poor” at the mid-reservoir location.
It should be noted that chlorophyll concentrations in Tellico Reservoir are assessed relative to expectations for the Blue Ridge Ecoregion, which has naturally low nutrient concentrations. Therefore, chlorophyll concentrations are expected to be much lower in Tellico than in other Tennessee Valley reservoirs located outside the Blue Ridge Ecoregion, such as Fort Loudoun Reservoir.
The fish assemblage rated “good” at the forebay and “high fair” at the mid-reservoir. Historically, ratings for the fish assemblage have fluctuated between “good’ and “fair” at both locations. In 2021, a total of thirty-eight species were observed. Bluegill, spotfin shiners, and brook silversides accounted for a significant portion of the fish collected. Fish diversity was similar to long-term averages, but fish abundance, especially at the mid-reservoir location, was less than expected.
Bottom life rated “poor” at the forebay and “low fair” at the mid-reservoir. Bottom life has rated “poor” at both monitoring locations all previous years because few organisms were collected, and most were species capable of tolerating a wide range of environmental conditions. Low dissolved oxygen concentrations and cold temperatures in the lower water column are likely factors contributing to the rating.
Sediment samples were not collected from Tellico Reservoir in 2021. Sediment quality was assigned a “good” rating for both monitoring locations based on sampling results from 1994 through 2019. Sediment quality has rated “good” in most years, but the detection of PCBs or pesticides (chlordane and aldrin) and/or elevated levels of arsenic has resulted in some “fair” ratings. Arsenic occurs naturally in the soils and concentrations in sediments deposited in the reservoir are generally near – slightly above or below – suggested background concentrations. The pesticides chlordane and aldrin were detected in sediment samples collected from Tellico Reservoir in the early 1990s. These pesticides were banned from use in the 1970s and 1980s. However, they continue to be detected sporadically in sediments because of their persistence in the environment. Similarly, PCBs were banned from commercial production in 1979, though they may be present in products and materials produced before the ban. PCB concentrations have, however, declined in fish samples collected from Tellico Reservoir.
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 Tellico Reservoir, visit the Tennessee Wildlife Resource Agency Fishing Guide.