Dormant water hyacinths. (Photo: Contributed)

Recent abnormally cold temperatures are uncomfortable yet beneficial for recreational boaters and swimmers who battle the waterweeds in area lakes.

“Mother Nature is the best aquatic plant management tool we have,” said Brett Hartis, TVA’s lead aquatic plant biologist. “Many invasive plants cannot handle extended deep cold snaps like we’ve seen so far in January.”

TVA reached near-record power demand in January because the average temperature was below freezing for at least 10 days. To meet the demand for power, TVA relied heavily on hydropower, dropping some reservoirs by about 2 feet below normal levels.


A good year expected
Because the past several winters have been so mild, there has been an increase in aquatic plant growth.

“The lower water levels expose invasive plant beds to the cold, and most invasive plants can’t tolerate the cold like native plants can,” Hartis said. “While there are no guarantees, Mother Nature should help this summer’s boaters and swimmers by controlling invasive plants in exposed areas along the shoreline.”

TVA sees keeping the reservoirs healthy as a top priority. According to a 2017 University of Tennessee study, recreation on the Tennessee River and its reservoirs is worth about $12 billion to the local economy and creates about 130,000 jobs each year.

TVA manages aquatic plants in developed public access areas on its reservoirs on an as-needed basis when recreational use and/or access becomes seriously hindered. Homeowners are allowed to control aquatic plants along their property as long as they follow all state herbicide application laws.

Hartis said he’ll know just how effective Mother Nature has been when spring gets here.

“We are expecting to see a significant visible reduction in new growth along the shoreline,” he said.

Fishermen shouldn’t worry
TVA reservoirs are known nationwide for their prime sport fishing. Hartis, an avid angler himself, knows the positive aspects aquatic plants have on reservoir fish habitats.

“The winter weather will only affect shoreline plants where the plant bed is exposed to the cold,” he said. “Submerged plants like hydrilla are not affected.”

Hartis said that some of his secret fishing holes may have to change this summer.

“Good fishermen can easily adjust,” he said. “That is why they call it fishing and not catching.”

Hartis expects the access will be much improved and that he and other anglers will still be able to pull monster-size fish out of the reservoirs this summer.

Ways you can help
TVA could use your help in controlling aquatic plants and keeping invasive species out of our reservoirs. To help control invasive plants, Hartis recommends:

—Keep it clean: Remove all plant material from boats, trailers, bilges, live wells and any marine equipment. This helps prevent aquatic species from being introduced into other reservoirs.

—Native water gardening only: Plant only native species around shorelines. Though non-native species like ornamental lilies and water hyacinth are beautiful, they will quickly spread if introduced into the river.

—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 submerged again. Consider visiting nonaffected reservoirs only after you have cleaned, drained and dried your boat.

—No dumping: Refrain from dumping unwanted aquarium or water garden plants into nearby streams and rivers. Dispose of any unwanted plants in the garbage.

Click here for a guide to aquatic plants, including how to tell them apart, how to fish them, and how to understand when and why they need management.