The ecological health of Cherokee Reservoir rated poor in 2012 consistent with most previous years. Cherokee rated fair in 1995 and 2008. This was because several ecological indicators concurrently rated at the upper end of their historical range. Cherokee is a relatively deep storage impoundment with a long retention time and plenty of nutrients, resulting in low dissolved oxygen levels and high chlorophyll levels.
As in previous years, dissolved oxygen rated poor at both monitoring locations. Much of the water column had low dissolved oxygen levels during the summer months, and there were extended periods of time when virtually no oxygen was present in the water near the bottom. TVA has installed aeration equipment to add oxygen to the deep water above Cherokee Dam and to improve conditions immediately downstream in the Holston River. Learn more about these improvements.
Chlorophyll rated good at the forebay but poor at the mid-reservoir monitoring location because concentrations were elevated during several sample periods. Chlorophyll typically rates poor or at low end of the fair range at the mid-reservoir location. Ratings for the forebay site have fluctuated between good, fair and poor; annual variations in the amount of rainfall and runoff have been an important factor.
The fish community rated good at the forebay and fair at the mid-reservoir monitoring location. The fish community has consistently rated fair or at the low end of the good range. Typically, a good variety of fish are collected at both monitoring locations, but a majority of the individuals collected are species that are more tolerant of degraded water quality.
Bottom life rated poor at both monitoring locations. Ratings for bottom life have fluctuated between fair and poor. However, most of the animals collected each year are those capable of tolerating poor water quality conditions. Fair ratings typically are the result of improvements in the numbers of tolerant organisms collected rather than an improvement in the variety of organisms.
Sediment quality rated fair at both monitoring locations. PCBs were detected in samples from the forebay and the concentration of copper was slightly elevated at the mid-reservoir. Copper concentrations have been elevated most years at the mid-reservoir location. Chlordane, a pesticide previously used to control termites and crop pests, has been found in some previous years at both locations.
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 Cherokee Reservoir, visit the Tennessee Wildlife Resource Agency.