Hi-Tech Solution to Aquatic Weed Monitoring

TVA’s Dr. Brett Hartis is a man with a mission: to control aquatic weeds, which can overtake TVA reservoirs. Now he’s using the latest digital technology to see the underwater world and get a jump on nuisance plants before they get out of control.

The summer heat came early to the Tennessee Valley, upping the pressure for Dr. Brett Hartis, Tennessee Valley Authority aquatic plant management specialist, to get his job just right. He is charged with the task of monitoring and managing nuisance aquatic plants in the Tennessee River system.

“We have forty-nine reservoirs and over 11,000 miles of shoreline in the [Tennessee Watershed] system,” says Hartis as he looks out over the green of various aquatic plant species that lie just beneath the water on Watts Bar Reservoir. “We have to get it just right to keep a balance for fisherman and recreational boaters.”

It’s a tense situation. Fishermen love the weeds, as they provide habitat for monster bass and other fish species. Recreational boaters often hate the weeds, as they can impede or even block lake access. Keeping everyone happy is a challenge Hartis deals with every day.

Digital Weed Solution

Over the roar of the airboat Hartis can detect the satisfying “ping” emitting from the latest hi-tech hydroacoustics gadget mounted to his craft as he skims across Watts Bar surveying aquatic vegetation.

The main target for today: Hydrilla. Hydrilla, native to Asia, was introduced into waters of the United States in the 1950s and 1960s primarily as a result of the booming aquarium plant trade. Now Hydrilla calls several TVA reservoirs home—Kentucky, Pickwick, Wheeler, Guntersville, Nickajack, Chickamauga and Watts Bar just to name a few.

“We’re using hydroacoustics very similar to what fishermen use,” says Hartis. “But instead of looking for fish or submersed structure, we are generating detailed vegetation maps in the water column.”

According to Hartis, hydroacoustics saves his team a tremendous amount of time and money, all of which is invested back into TVA’s aquatic plant management program. “Before hydroacoustics we had to stop and generate vegetation maps by hand—using various techniques—and we never really got a good look under the water.” Now Hartis says he can skim across the water mapping as he goes, and only slow down to identify tricky plant species that look identical to the untrained eye.

Seated on his airboat, Hartis collects data, including water depth, vegetation density, and plant species and uploads it to the cloud so it is ready for him at his office in Guntersville, Ala. From there he creates detailed vegetation maps and devises site-specific plans for management of nuisance vegetation near developed public access areas.

Hartis explains that each reservoir is unique and aquatic plant distributions can fluctuate dramatically from one year to the next based on various natural factors including flow, weather, etc. “Being able to quickly map the areas we monitor each year makes sure that we implement management in a timely manner,” he says. “There is no ‘one solution’ when it comes to aquatic plant management. You have to use the data and manage these areas accordingly, most often based on the species present in the area. Hydroacoustics give us the empirical data we need to keep public access areas like boat ramps, swim beaches and parks ready for the millions of people who use them for recreation each year.”

Hartis and his team regularly meet with reservoir groups to talk about aquatic plants and show off the latest technology used to monitor them.

No DYI Weed Control Please

TVA manages aquatic weeds in developed public access areas—boat ramps, swim beaches, public parks, etc., on an as need basis. Private property owners might be interested in having their water use facilities—docks, marinas, etc.—treated for nuisance aquatic plant growth. Some states regulate the application of aquatic herbicides, often requiring that a licensed applicator service be used. To keep property owners on the right side of the law and protect the environment, Hartis recommends that property owners be aware of and follow state law in their areas.

“The law is one reason, but another reason is that most property owners are not equipped to manage these plants effectively. Identification of each species and calculating vegetation density, water depth, and flow rate are integral to success in management,” says Hartis. “Hiring a knowledgeable applicator can save property owners a considerable amount of time and investment by leaving this work to a professional.”

To help property owners, TVA can provide a list of professionals licensed to do work in each state.

How You Can Help

The Tennessee River runs 675 linear miles and the watershed spans seven states, so battling invasive plants is a year-round job for Hartis’ team. Once established, many of these species may cause economic and environmental impacts to the reservoir, so keeping invasive plants out in the first place is always the best plan.

TVA needs your help to control aquatic plants and keep invasive species out of TVA reservoirs.

According to TVA, invasive aquatic plant species like Hydrilla, Eurasian watermilfoil, curly leaf pondweed and water hyacinth were likely unintentionally spread along the Tennessee River by hitching rides on boat trailers or by people dumping fish tanks and water garden plants into the river.

“Invasive aquatic plants are notorious for their ability to grow in our waters!” says Hartis. “Without any naturally occurring predators and disease, these species can grow exponentially. Even one plant fragment can take root, grow, and spread if conditions are right and once they are established, they are likely going to be here forever.”

To help Hartis and TVA control invasive plants he recommends:

  1. Keep it Clean—Remove all plant material from boats, trailers, bilges, live wells and any marine equipment. This will prevent aquatic species from being introduced into other TVA reservoirs.
  2. Native Water Gardening Only—Plant only native species around shorelines. While non-native species like ornamental lilies and water hyacinth are beautiful, they will quickly spread if introduced into the river.
  3. Drain and Dry—When visiting reservoirs with known invasive plants, make sure all equipment is dry and free from fragments. Even completely dry fragments have the potential to grow once submersed again. Consider only visiting non-affected reservoirs after you have cleaned, drained and dried your boat from other trips.
  4. No Dumping Please!—Please refrain from dumping unwanted aquarium or water garden plants into nearby streams and rivers. Dispose of any unwanted plants in the garbage.

Learn more about aquatic plants and how to fish them in the Tennessee River system at TVA.com.

Valley Lakes Worth Billions

A new study from TVA and the University of Tennessee Institute of Agriculture shows that the annual value of recreation on the Tennessee River reservoir system to the region is nearly $12 billion annually—or approximately $1 million per shoreline mile. What's more, there are approximately 130,000 associated jobs. Read all the details about this groundbreaking study.