Douglas
Reservoir
Ecological
health rating
Douglas Reservoir rated poor in 2011. Douglas has rated either poor or at the low end of the fair range in previous years.
TVA monitors two locations on Douglas Reservoir—the deep, still water near the dam, called the forebay, and the middle part of the reservoir—usually on a two-year cycle.
Douglas
Reservoir Ecological Health Ratings, 1994-2011
Click chart for raw
data.
The table below
shows the ratings for individual ecological health indicators at Douglas
in 2011. These ratings are briefly explained in the paragraphs that follow.
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Ecological
Health Indicators at
Douglas Reservoir, 2011
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Monitoring
locations
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Dissolved
oxygen
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Chlorophyll
|
Fish
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Bottom
life
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Sediment
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| Forebay |
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| Mid-reservoir |
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Dissolved oxygen
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. TVA has installed aeration equipment to add oxygen to the deep water near the dam and to improve conditions downstream from the dam in the French Broad River. Learn more about these improvements.
Chlorophyll
Chlorophyll rated good at the forebay and poor at the mid-reservoir monitoring location. Summer chlorophyll averages are generally higher at the mid-reservoir site, rating poor in most years. Chlorophyll ratings at the forebay have been variable, typically rating good or fair, except in 2003 when it rated poor. Rainfall and the resulting runoff have played a significant role in year-to-year variation.
Fish
The fish community rated good at both monitoring locations. As in most previous years, TVA collected a good number and variety of healthy fish. The fish community at the mid-reservoir location received a fair rating in 2007, and it was the lowest score to date for Douglas Reservoir. The catch rate was relatively low and fewer fish species were collected than normal. This was because sampling results at this location were affected by low water levels, a result of the extremely dry conditions.
Bottom life
Bottom life scored at the low end of the fair range at both monitoring locations. As in previous years, TVA found relatively few animals in samples collected from the reservoir bottom, and the animals collected were primarily species capable of tolerating poor conditions.
Sediment
Sediment quality rated fair at both monitoring location. PCBs were detected in the sediment samples from both locations, and the arsenic concentration in the sample from the forebay was at the upper end of the expected range for background levels. Low levels of the pesticide chlordane were detected at the sites in some previous years.
See definitions of
ecological health indicators and monitoring locations.
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Fish
consumption advisories
Douglas Reservoir - 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 Douglas Reservoir, visit the Water Quality Division of Tennessee Department of Environment & Conservation’s web page. http://www.tn.gov/environment/water.shtml
Tennessee Valley Authority
