Tims Ford Reservoir

Tims Ford Reservoir rated poor in 2010, similar to previous years. Consistent issues are low dissolved oxygen levels in the lower water column and poor ratings for bottom life. Lower ratings for chlorophyll at the mid-reservoir location have been an issue in some years and chlorophyll rated poor at this location in 2010.

TVA monitors two locations on Tims Ford 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.

Ecological Health Indicators at Tims Ford Reservoir — 2010

Monitoring location Dissolved
oxygen
Chlorophyll Fish Bottom
life

Sediment
Forebay Poor Fair Good Poor Fair
Mid-reservoir Poor Poor Good Poor Good

Dissolved oxygen

As in previous years, dissolved oxygen rated poor at both monitoring locations. Oxygen levels were below two milligrams per liter in portions of the lower water column from June through October at both monitoring locations, including extended periods of time when some area of water was completely devoid of oxygen. 

Chlorophyll

Chlorophyll concentrations were higher than expected resulting in a fair rating at the forebay and a poor rating at the mid-reservoir location. Chlorophyll at the forebay has rated good more years than fair, but ratings at the mid-reservoir have varied between good, fair and poor. Chlorophyll concentrations have varied in response to the timing and amount of rainfall. However, average chlorophyll concentrations have shown a general trend of increasing at the mid-reservoir location since TVA began monitoring Tims Ford in the early 1990s.

Fish

The fish assemblages rated good at both monitoring locations. The fish assemblage at the mid-reservoir received its highest score to date, placing it more to the middle of the good range. In previous years, the fish assemblage at both locations has scored fair or “low good.”  Typically, a good variety of fish are collected, but a large number of them are species such as bluegill and spotfin shiner that are more tolerant of degraded water quality.

Bottom life

As in previous years, bottom life rated poor at both monitoring locations because few animals were found and all were species able to tolerate poor conditions. Low dissolved oxygen levels near the reservoir bottom are a likely contributing factor.

Sediment

Sediment quality rated fair at the forebay due to elevated levels of arsenic and nickel. The mid-reservoir location received a good rating.  Sediment quality typically rates fair at the forebay and good or fair at the mid-reservoir location. Nickel has exceeded expected background levels at the forebay location in all previous years of monitoring, while arsenic exceeded those levels at the forebay during one other monitoring year (2002) and at the mid-reservoir in 2008. Low levels of chlordane also have been detected at the mid-reservoir location in the past (1996, 1998 and 2002). 

Fish consumption advisories

Tims Ford 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 Tims Ford Reservoir, visit the Tennessee Wildlife Resource Agency's fish guidebook.