More Air Down There

Thursday, September 28, 2017 - by TVA Newsroom
Reservoir Release Improvements program manager Jeff Ogden holds lengths of diffuser line, which will be installed on lake beds to infuse oxygen into the water below TVA dams.
Reservoir Release Improvements program manager Jeff Ogden holds lengths of diffuser line, which will be installed on lake beds to infuse oxygen into the water below TVA dams.

TVA’s Reservoir Release Improvements (RRI) program is out to save lives. Sure, they’re little lives; in some cases, tiny ones. But in the grand scheme of the Tennessee Valley’s ecosystem, aquatic invertebrates, mussels and fish are each a vital link. And in TVA’s view, with the running of dams on the Tennessee River system comes the responsibility of caring for their destinies. And that means adding oxygen to the tailwaters below the dams it uses to generate power.

These waters are, by nature, cold and deep, and—particularly during times of warm weather—are liable to get stressed as water with a higher oxygen content remains in the upper layers of the water column in a natural process called thermal stratification. Bottom layers become increasingly starved for oxygen as they are used by organic materials or swept into the reservoir during the process of generation. For bottom-dwelling aquatic life, or for fish that live and/or spawn in cold water, conditions can grow increasingly hostile.

Reservoir Release Improvements program manager Jeff Ogden holds lengths of diffuser line, which will be installed on lake beds to infuse oxygen into the water below TVA dams.

Mr. Ogden is program manager of TVA’s RRI Program, and he can tell you flat out: There is no federal requirement that TVA do anything about this situation. There’s no mandate for a remedy. And yet, Ogden is overseeing a massive effort to improve oxygen diffuser equipment currently in place at nine of TVA’s power producing dams and one non-power producing dam. And he’s passionate about collecting and sharing data with state agencies that also care about water quality.

“Taking care of the environment and keeping our reservoirs healthy is an important part of our operations—they go hand in hand,” he said. “Both are part of our mission, and we are doing our part to be good stewards of the environment to improve water quality.”

It’s All About the Oxygen

TVA has devised many ways to add oxygen back to the water, including:

  • Aerating Turbines: Dedicated turbines add oxygen to the water during generation.
  • Surface Water Pumps: These pumps, which look a little like large ceiling fans, are positioned above a dam’s intakes and push oxygen down to the turbine intakes prior to generation.
  • Aerating Weirs: These are small dams designed to mimic waterfalls, adding oxygen as water tumbles over their walls.
  • Low-Pressure Blowers: As advertised, these aerators blow oxygen into the water as it flows through the dam.
  • Oxygen-Injection Systems: A system of oxygen tanks feed tubing that lies on the lakebed (not unlike garden hoses) and diffuses oxygen into the water prior to and during generation.

It is the latter of these aeration technologies that TVA will begin installing at Cherokee dam in FY18. Similar projects are currently underway at Watts Bar and Hiwassee dams. All three are oxygen-injection system replacement projects in which diffuser line is welded together and installed in the reservoir.

These are large projects with highly experienced personnel both supporting and performing the field work. “This technology was developed at the TVA Engineering Laboratory in Norris,” Mr. Ogden said. “TVA is a leader in oxygenation technology. We developed this technology and have made design and construction process improvements through the years.” In fact, so great is TVA’s leadership in the field that it advises even the U.S. Army Corps of Engineers on oxygenation at the dams it manages. The RRI program has a Wildlife Habitat Council conservation certification as a result of the ongoing efforts to create a healthy environment for aquatic habitat downstream of its dams.

Once in place, oxygen diffuser technology is managed to keep dissolved oxygen levels in the water at 4-6mg/L; without the intervention, levels would likely be 0-3 mg/L—far less likely to sustain life. Moreover, the TVA’s combined oxygen improvement efforts affect up to 300 miles of river downstream from TVA dams.

Species that have benefited from oxygenation efforts include the vulnerable boulder darter (which lives mainly below Tims Ford Dam) and the formerly endangered lake sturgeon (pictured at top of page), which has enjoyed a system-wide comeback in recent years, as well as many varieties of fish, mussels and other aquatic invertebrates, including mayflies, stoneflies and caddisflies.

All told, that’s a lot of lives saved. Perhaps the Tennessee Valley’s most vulnerable aquatic wildlife can breathe a little easier knowing TVA has their back.

Sturgeon
Sturgeon


A Canoe Tour On Lookout Creek Set For July 27

Chickamauga and Chattanooga National Military Park would like to invite the public to participate in a free, two-and-a-half hour, family-friendly canoe tour with a ranger on Friday, July 27, at 9 a.m. National Park Parnters and the Friends of Outdoor Chattanooga will sponsor an event where visitors will paddle the quiet waters of Lookout Creek and learn about the rich Civil War ... (click for more)

TWRA Working To Stop Asian Carp

Biologists with TWRA monitor fish populations throughout the state, including species such as invasive forms of Asian carp. There are four species of Asian carp currently in Tennessee including bighead, black, grass and silver carp. Although concerned with all invasive species, TWRA focuses on the impact of silver carp which have greatly impacted west Tennessee.   ... (click for more)

Former Dalton High School Teacher Who Fired Gun At School Pleads Guilty, Sentenced To 2 Years

Jesse Randall Davidson, 53, formerly of 5219 Hwy 11, Rising Fawn, and formerly a teacher at Dalton High School, entered a guilty plea to criminal damage to property in the first degree, carrying a weapon within a school safety zone and disrupting the operation of a public school.  He was sentenced to serve two years in prison followed by eight years on probation on the first ... (click for more)

Firefighters Battle 2-Alarm Fire On Workman Road Tuesday Morning

Chattanooga firefighters were dispatched at 6:03 a.m. on Tuesday, to a commercial fire at 400 Workman Road. When the first firefighters arrived on the scene, flames were shooting through the roof and the request was immediately made for a second alarm response. The flames could be seen for miles as a total of 13 fire companies rushed to the scene. The large, two-story ... (click for more)

Bill Lee Is Great For Tennessee

I had the opportunity to meet Bill and Maria Lee at the grand opening of his Chattanooga Campaign HQ. He delivered, what was by most accounts, a showstopper speech at the Statesman’s dinner in Nashville the night before. He and Maria should have been worn out, but if they were, they really showed very little sign of it. His energy level, for a guy that couldn’t have gotten more ... (click for more)

A Successful East Ridge Bake Sale

Saturday's event at the Camp Jordan Pavilion was nothing more than extraordinary, if not history making.  Alongside the threatening eminent domain letters the citizens of East Ridge received, a Union was formed amongst the East Ridge Police Department.  Coming to City Council the night of April 26, I had only one thing I was focused on: eminent domain.  ... (click for more)