Utility makes progress against invasive plant

Central Arkansas Water has made progress in its efforts to attack the invasive aquatic plant known as hydrilla in Lake Maumelle, the utility’s board of commissioners were told during a recent meeting.

The utility is in the second year of a roughly five- to eight-year herbicide treatment plan, Water Quality Manager Sharon Sweeney told commissioners on Thursday.

The second annual drawdown of Lake Maumelle took place beginning at the end of October, she said. Despite rainfall, the drawdown was successful at exposing the shoreline, including during some very cold temperatures, Sweeney said.

Rain also occurred during the previous lake drawdown, she recalled, remarking that “one thing we have learned in the past two years, if we want to bring rain into the area, we should lower the reservoir.”

Nevertheless, the hydrilla tubers were damaged, meaning that when the utility performs the next application of an herbicide this spring, “the plants will be stressed and so they will be growing with vigor, and when we apply the herbicide, they’ll have a stronger uptake,” Sweeney said. “So the drawdown strategy is working and it is helping to control the population.”

The fluridone-based product, which inhibits photosynthesis in the plants, is believed to be safe to use in drinking-water reservoirs. “We saw no issues last year,” Sweeney said.

Like last time, a total of 58 treatment zones will be hit with the herbicide systematically from a boat while using a GPS system to follow the outline of the tracts, according to Sweeney.

Officials anticipate using approximately 23,000 pounds of the product this year, she said. Because they will be able to use the remaining product from last year, the utility does not have to spend any money this year to acquire it, according to Sweeney.

Commissioners were shown photos of the lake to illustrate the difference between May 2022, when hydrilla was visible growing in the lake, to July 2023. An aerial photo taken at that time showed a section of lake that was clear of the invasive vegetation.

Herbicide application is scheduled to begin this week. The lake is expected to be closed to the public all week and will reopen as soon as the treatment is finished, Sweeney said.

In addition to the herbicide treatment, officials plan to install two boat wash stations, she said, one at WestRock Landing and the other at the Sleepy Hollow access.

“We’re spending a great deal of time and energy and money to keep invasive species out of the lake, and these boat wash stations will help us,” Sweeney said.