Cherokee
Reservoir
Ecological
health rating
Cherokee Reservoir rated fair in 2008, similar to 1995. This was because several ecological indicators concurrently rated at the upper end of their historical range. In all other years the ecological condition of Cherokee reservoir has rated poor. 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.
TVA monitors two locations on Cherokee Reservoir — the deep, still water near the dam, called the forebay, and the middle part of the reservoir. Monitoring is usually done on a two-year cycle.
Cherokee
Reservoir Ecological Health Ratings, 1994-2008
Click chart for raw
data.
The table below
shows the ratings for individual ecological health indicators at Cherokee
in 2008. These ratings are briefly explained in the paragraphs that follow.
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Ecological
Health Indicators for
Cherokee Reservoir, 2008
|
|
Monitoring
locations
|
Dissolved
oxygen
|
Chlorophyll
|
Fish
|
Bottom
life
|
Sediment
|
| Forebay |
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|
|
|
|
| Mid-reservoir |
|
|
|
|
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Dissolved oxygen
As in previous years, dissolved oxygen rated poor at both sampling 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
Chlorophyll rated good at the forebay and fair at the mid-reservoir monitoring location because concentrations were slightly elevated during several sample periods. Chlorophyll typically rates poor 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.
Fish
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 many of the species are tolerant of degraded water quality.
Bottom life
Bottom life rated fair at both monitoring locations. Bottom life typically rates fair at the forebay. Ratings at the mid-reservoir have fluctuated between fair and poor. As in previous years, the animals collected were primarily species capable of tolerating poor conditions.
Sediment
Sediment quality rated good at the forebay and fair at the mid-reservoir because concentrations of copper were slightly elevated. 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.
See definitions of
ecological health indicators and monitoring locations.
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Fish
consumption advisories
Currently, there are no fish
consumption advisories on Cherokee Reservoir. TVA collected channel
catfish and largemouth bass from the reservoir for tissue analysis
in the autumn of 2006. With the exception of mercury concentrations in largemouth bass, contaminant concentrations were either below detectable
levels or below the levels used by the state of Tennessee to issue
fish consumption advisories. TVA will collect fish from Cherokee again
in the autumn of 2010.
Tennessee Valley Authority
