MATTOON — Blue-green algae developing at Lake Paradise last summer grew so severe that it created strong odors and led to a swimming ban.
Now, the city of Mattoon is testing sonic waves as a means of controlling the algae. On Aug. 20, the Mattoon City Council voted to rent three Quattro-DB sonic wave algae control units from Green Water Solutions of Indianapolis, Ind. The city deployed two of these floating units on the water last week and the third on Friday.
Watching one of those units deploy on Friday was Jerry Curry of Decatur, who said the drive was well worth it for the fishing experience at Lake Paradise. He said the lake has a nice layout and good population of catfish, and he was happy the city of Mattoon is taking steps to protect the 174-acre lake and its fish.
"I have had some nice ones today," Curry said of the bites on his fishing lines.
Certain types of blue-green algae can release toxins that are harmful to people and animals, and the toxins can build up in the gut and muscle of fish swimming in affected water.
Mattoon engineering technician Ethan Ervin said the amount of blue-green algae at Lake Paradise has not been bad this year because the summer has been cooler overall. He said the concentration of algae has not reached levels that are significant enough to cause any issues this year. Still, Ervin said the city wants to be prepared for a future algae outbreaks.
"It's becoming more and more of an issue," Ervin said of blue green algae outbreaks across much of the United States. "We are just trying to get ahead of it."
The city began researching control options after the blue-green algae outbreak last summer at Lake Paradise. The city reported at the time that heavy rainfall had increased the amount of phosphorous and nitrogen that was running off from farm fields into Lake Paradise, and that this runoff provided more nutrients for algae to consume and boost reproduction.
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Ervin said he appreciates that the sonic wave algae control units are chemical free. The city's research found that conventional chemical treatment options are not recommended because the killed algae release harmful chemicals if the cell walls are disrupted.
Mattoon water plant operator A.J. Cobble said chemical treatment options such as copper sulfide can cause fish kills while controlling algae. He noted that regular fishermen and weekend anglers are drawn to the thriving population of fish in Lake Paradise.
"I would hate to sacrifice something like that," Cobble said.
The city staff's algae control research led them to the sonic wave algae control unit. Public Works Director Dean Barber reported to the council that these units emit sonic waves that cause the algae to sink to the bottom of the water, disabling them from collecting sunlight and continuing to populate.
The manufacturer of the Quattro-DB units reports that these devices work in harmony with fish and other aquatic wildlife, aquatic plants, bio-solids and planktonic organisms other than algae.
Each square-shaped unit is powered by solar-charged batteries and floats on a pontoon that is anchored to the lake floor like a buoy. Long wires sprout out in different directions from short pillars at each corner of the unit to deter birds from sitting on top of this device.
The city is using water service rate revenue to fund the $22,700 rental from Green Water Solutions. Ervin said the city will test the sonic wave algae control units for 90 days, examine the results, and then determine if it will purchase units for use at Lake Parade and Lake Mattoon.
"We do have the flexibility to move them around if needed," Ervin said.