Wheeler Reservoir

Ecological health rating

Wheeler Reservoir rated poor in 2007, compared to either good or fair in all previous years. Generally, lower ecological health scores occur during years with lower flows when, typically, chlorophyll concentrations are higher and dissolved oxygen concentrations are lower. This pattern held true for 1999, 2001, and 2007, which were all characterized by low flows. 2007 was the driest year in 118 years of record.

TVA monitors four locations on Wheeler Reservoir—the deep, still water near the dam, called the forebay; the middle part of the reservoir; the Elk River embayment; and the riverlike area at the extreme upper end of a reservoir, called the inflow—usually on a two-year cycle.

Wheeler Reservoir Ecological Health Ratings, 1994-2007

Click chart for raw data.

The table below shows the ratings for individual ecological health indicators at Wheeler in 2007. These ratings are briefly explained in the paragraphs that follow.

Monitoring locations	Dissolved oxygen	Chlorophyll	Fish	Bottom life	Sediment
Ecological Health Indicators at Wheeler Reservoir, 2007
Forebay	Poor	Poor	Good	Poor	Good
Mid-reservoir	Good	Poor	Fair	Good	Good
Elk River embayment	Poor	Poor	Fair	Poor	Good
Inflow			Fair	Good
Dissolved oxygen Dissolved oxygen rated good at the mid-reservoir location and poor at both the forebay and Elk River embayment due to low concentrations (less than two milligrams per liter of oxygen) in the lower water column during the summer. Dissolved oxygen has rated good at the mid-reservoir location in all previous years, but ratings have varied between good, fair and poor at the forebay and embayment locations, primarily due to reservoir flows. Chlorophyll Chlorophyll rated poor at all locations monitored. Summer average chlorophyll concentrations were elevated in response to the record dry year and associated low flows. Chlorophyll typically rates poor at the forebay and Elk River embayment, but ratings have varied between good, fair and poor at the mid-reservoir location. Fish The fish community rated fair at all monitoring locations, except for the forebay which rated good. Ratings for the fish community have fluctuated between good and fair at each location. 2005 was the only year the fish community has rated good at all locations. Bottom life Bottom life rated poor at the forebay and Elk River embayment and good at the mid-reservoir and inflow monitoring locations. The lower ratings were due to relatively sparse populations, predominantly composed of animals able to tolerate poor water quality. Sediment Sediment quality rated good at all locations monitored. No pesticides or PCBs were detected, and the concentrations of metals were within expected background levels. Sediment quality typically rates good, although it rated fair at the mid-reservoir location in 2003 due to the presence of low levels of chlordane (a pesticide previously used to control termites and crop pests). See definitions of ecological health indicators and monitoring locations.

Fish consumption advisories

There is one fish consumption advisory for Wheeler Reservoir. The state of Alabama advises people not to eat smallmouth buffalo or bigmouth buffalo from the Huntsville Spring Branch or the Indian Creek embayment on Wheeler Reservoir because of DDT contamination.

TVA collected channel catfish and largemouth bass from the reservoir for tissue analysis in fall 2005. The results, which were similar to those of previous years, will be provided to state agencies in Alabama. TVA will analyze fish from Wheeler Reservoir again in autumn 2007.

Wheeler Reservoir is located on the Tennessee River in north central Alabama.