Douglas Reservoir rated “fair” in 2016. Douglas rated either at the low end of the “fair” range or “poor” in previous years.
The ecological health of Douglas 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 Douglas Reservoir—the deep, still water near the dam, called the forebay (French Broad River Mile (FBRM) 34.5); and the middle part of the reservoir (FBRM 51.0).
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>72 = Good
59-72 = Fair
<59 = Poor
Consistent with findings from previous years, dissolved oxygen concentrations at the forebay and mid-reservoir monitoring locations were very low in the bottom half of the water column during the summer, resulting in “poor” ratings for this indicator.
As part of TVA’s Reservoir Release Improvement Program, TVA has installed aeration equipment at Douglas Dam to improve the quality of water downstream from the dam in the French Broad River. Learn more about these improvements.
Chlorophyll rated “good” at the forebay and “poor” at the mid-reservoir monitoring location. Summer chlorophyll averages are generally higher at the mid-reservoir location, rating “poor” in most years. Chlorophyll ratings at the forebay have rated “good” or at the upper end of the “fair” range, except in 2003 when it rated “poor”. Rainfall and the resulting runoff have played a significant role in year-to-year variation.
Consistent with most previous years, the fish assemblage rated “good” at both monitoring locations. Thirty-seven different fish species were observed reservoir wide, including a “good” variety of top carnivores (e.g., largemouth bass), sunfish (e.g., bluegill) and benthic invertivores (e.g., black redhorse). Forage fish such as gizzard shad and spotfin shiners also were abundant. Fish health was assessed a “good” rating with low incidences of disease and parasites.
Bottom life scored at the low end of the “fair” range at both monitoring locations. As in previous years, TVA found a limited variety of organisms in samples collected from the reservoir bottom, and these were primarily species, such as midges and worms, capable of tolerating low dissolved oxygen conditions.
Sediment quality rated “good” at both monitoring locations. Low levels of PCBs and the pesticide chlordane have been detected in sediment samples from both monitoring locations in some previous years, causing sediment quality to rate “fair”.
TVA maintains a program to examine contaminants in fish fillets 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 Douglas Reservoir, visit the Tennessee Wildlife Resource Agency.