Boosting Oxygen in the Water
Infusing deep waters with life-giving oxygen preserves cold-water species.
- In summer, a natural process called thermal stratification occurs in deep tributary waters where warm oxygen-rich water floats
- The bottom layer can become starved for oxygen as it is used by organic materials or swept into the reservoir.
- This stresses cold-water wildlife.
- TVA has developed some ingenious solutions for aerating this cold water, which it deploys on a dam-by-dam basis.
To help cold-water species continue to thrive, TVA has developed some ingenious solutions, which it employs on a dam-by-dam basis. There are five of key technologies:
At some dams, TVA uses aerating turbines to draw air into the water as power is being generated; at other dams, turbines exist just for the purpose of aerating the water.
Surface Water Pumps
At other dams, such as Douglas, surface water-pumps (which look a bit like big ceiling fans) are positioned just above the dam’s intakes and push oxygen-rich water downward during generation.
Oxygen Injection Systems
At some reservoirs, oxygen is injected into the water before it enters the dam’s intake. The system consists of an oxygen tank and evaporators on the bank that are connected to perforated hosing suspended above the reservoir floor upstream of the dam. (It’s the same kind of hosing used in gardens for irrigation.) Gaseous oxygen is pumped through the hosing, creating oxygen bubbles delivered straight to the cold bottom layer.
These are small dams designed to mimic a natural waterfall, adding oxygen to the water as it plunges over the weir walls. Larger infuser weirs are also used, like the one pictured above, which resides at Chatuge Dam.
As advertised, these aerators blow air into the water as it flows through the dam.
With more oxygen in the reservoirs, TVA is able to fulfill its mission of being a good environmental steward, providing the right conditions for cold water species not only to survive but thrive.