Gainesville is thinking “outside” “the box to combat chronic taste and odor issues caused by historically high algae levels in Lake Sidney Lanier, its primary water source.
Although extensive and recurrent testing confirms taste and odor concerns are purely aesthetic, and not in any way a health concern, the city is hopeful ultrasonic algae control technology is the answer. At the City’s request, three MPC-Buoys were deployed in mid-January by LG Sonic, “pioneers in ultrasonic algae control,” with whom the Gainesville Department of Water Resources (DWR) partnered in December.
“As the 2025 taste and odor event continued, DWR staff continuously searched for additional remedies,” said Gainesville Water Resources Director Linda MacGregor. “We sought the input of national experts who identified this as an option worth testing.”
The science behind LG Sonic’s ultrasonic technology has the potential to reduce algae by 95% without chemicals, MacGregor added, stopping stubborn algae growth long-term without harming people, pets, other aquatic life or the lake itself.
The MPC-Buoys — “MPC” standing for “monitor, predict and control” — emit low-power ultrasound waves in the top water layer that block algae’s access to sunlight and nutrients, causing the algae to sink to the bottom and die off, where they decompose naturally.
This is made possible by generating a constant pressure cycle around the algal cells, which interferes with the algae’s buoyancy regulation, or its ability to reach the surface for sunlight and the bottom for nutrients. Instead, the algae remain suspended between the two — deprived of the optimal environment needed to thrive and multiply.
“By emitting sound waves that disrupt the buoyancy of algae, you’re preventing them from releasing the compounds that cause the musty taste and odor issues,” MacGregor said.
Additionally, the buoys are equipped with real-time water quality monitoring.
“They provide an overview of our water quality by collecting the following parameters every 10 minutes: chlorophyll α (green algae), phycocyanin (blue-green algae), pH, turbidity, dissolved oxygen and temperature,” MacGregor said. “Data is key when it comes to understanding this complex natural phenomenon.
“All utilities withdrawing water from both Lake Lanier and the Chattahoochee River are expressing these issues to varying degrees. Also, other lakes have experienced identical issues this year, more so than other years.”
The City’s new MPC-Buoys, secured under a six-month rent-to-own contract, were deployed in the immediate vicinity of the water intake at Riverside Water Treatment Plant (WTP).
“We are now gathering additional data to track the results,” MacGregor said. “It will be at least a month before we expect to see trends.
“We want to remedy the issue just as badly as residents want us to remedy the issue,” MacGregor said. “DWR staff have been working around the clock to address taste and odor concerns with every known solution, but unprecedented algae levels in Lake Lanier are proving more difficult to treat than in years past.”
MacGregor said these adjustments include:
• Collecting and analyzing lake samples three times weekly from multiple locations and depths to adjust chemical dosing and better understand trends
• Evaluating treatment options at both water treatment plants while relying on continued support from consultants, including Hazen and Sawyer, and Corona Environmental Consulting
• Adjusting withdrawal levels from Lake Lanier based on laboratory results
• Adjusting the powdered-activated carbon (used to remove algal tastes and odors) injection point in the treatment process
• Adjusting other treatment parameters for optimization while continuing to have concurrent compliance with dozens of safe drinking water requirements
• Having operators conduct jar tests and increase testing of multiple parameters to optimize treatment processes
• Increasing the pressure at Lakeside WTP so more of the system is fed from Lakeside as its removal has proved more successful than Riverside WTP
• Requiring plant operators to participate in weekly meetings with other utilities withdrawing from Lake Lanier and the Chattahoochee River
• Exchanging data and operational results with Gainesville’s peer utilities, including Forsyth and Gwinnett counties
“The City appreciates the public’s patience as taste and odor compounds continue to decrease,” MacGregor said. “In the meantime, we can assure you the water is safe to drink and use for other purposes, despite the earthy smell and taste caused by natural phenomena in the lake.”
For City-issued updates regarding taste and odor, please visit https://www.gainesville.org/518/Taste-Odor.
To learn more about LG Sonic, visit https://www.lgsonic.com/ultrasonic-algae-control/.