Scientist: High hopes for lake biofilters this season

CELINA - In just a few weeks, area treatment trains that filter out nutrients responsible for toxic blue-green algal blooms in Grand Lake will be turned on, and officials are shooting for the stars in 2025, with hopes of processing 1 billion gallons of water, compared to about 625 million gallons last year.

Stephen Jacquemin, an environmental sciences professor at Wright State University-Lake Campus, provided an update Saturday morning about the lake's treatment trains and also revealed that blue-green cyanobacteria at the moment is comprising only 15-20% of the total algal community in Grand Lake, which he called a very unusual - but positive - development.

"The wetlands are slated to be turned on here in the next couple of weeks," Jacquemin said at Lake Improvement Association's monthly meeting. "Things are starting to green up, and it's just incredible to see."

Jacquemin is optimistic about this year's treatment train cycle, in large part because the Prairie Creek treatment train is expected to be brought back up to speed.

The Prairie Creek treatment train, which has been plagued by pumping problems and other issues in recent years, operated at about a quarter of capacity in 2024. Energies have been focused on enhancing its pumping power.

"Pleased to say there's been improvements and some upgrades out there at the Prairie Creek pumping station, and so we've done a couple of test runs and filled those cells … with some of the creek water - and those pumps are moving at a minimum of two-and-a-half to three (times) what they were last year," he said.

Other long-term improvements will be necessary, but for this season, officials expect much higher volumes of water to flow through the Prairie Creek treatment train. If that happens, the overall volume of total processed water this year in the watershed should rise sharply.

"If we can get Prairie Creek operating like I think it can - and like it looks like it might - all season long, and we increase a little bit of pump capacity at Big (Chickasaw treatment train), which we're slated to be able to do, we should be able to reach a nice round number, right around a billion gallons," Jacquemin said. "That'd be incredible. A billion gallons is something we've never hit before."

Treatment trains - vegetative biofilters that remove nutrients from the water flowing into Grand Lake - have been established at Coldwater, Prairie, Beaver and Big Chickasaw creeks.

Nutrient runoff comes from many sources, but in the Grand Lake Watershed, studies show it's mostly from farmland in the 58,000-acre, livestock-heavy watershed.

"It's so critical that we have funding and dollars for conservation practices, not just to build wetlands, but also across our fields … and for our great producers to continue to implement the best management practices that they have been for so many years," Jacquemin said while touching on the importance of the H2Ohio program for water quality restoration and conservation.

Jacquemin estimated present algae levels at 300 micrograms of algae per liter - or at least before the area was hit with a deluge of rains, boosting nutrient loading into the 13,500-acre Grand Lake.

"That is in line with the past years, and so it's very, very typical for this time of the year. The algal biomass is starting to ramp up," he said.

What's unusual, though, is the makeup of that total algal biomass.

"The percentage of algae that is blue-green cyanobacteria algae, typically it's 90% of our algal community," Jacquemin said. "What we're seeing right now is remarkably … less."

He put the blue-green algae level at 15-20% of the total biomass. The rest consists of "a pretty healthy diversity of all the other flavors of algae that we've got," including, green, golden and brown algae.

Because the overall algal community is not primarily composed of blue-green algae, it's not producing many toxins.

"We're sitting at just under 3 micrograms per liter of total microcystin toxin," he said, noting it's far below advisory thresholds established by the state and World Health Organization. "Overall, this is good news, this is a good thing to see. So we're very happy about this, and we'll continue to come back and give updates. But for this time of year, we would expect to be up quite a bit from where we are right now."

But the state of the petri dish that is Grand Lake is given to fluctuations. Jacquemin expects an eventual shift toward a more blue-green cyanobacteria algae dominated system.

Treatment trains and manure best management practices have led to positive tangible results, but there's still a long way to go, Jacquemin said when questioned by an audience member about the efficacy of wetlands.

"When we look at how the levels of phosphorus compare to what they were 10-15 years ago with a system like Grand Lake St. Marys, you have to take care of the phosphorus coming into it before you can really get a handle on the phosphorus that's actually in the lake," he explained. "If you don't turn off the spigot, you don't turn off the phosphorus coming into the lake, it's really difficult to make any kind of traction."

The phosphorus already in the lake doesn't magically disappear, it's recycled.

"Phosphorus does not have an atmospheric component, so it doesn't move up into the atmosphere like nitrogen can. Phosphorous sort of cycles," he explained. "It can move from the sediment into the water column into the biovolume of the algae and so on and so forth. The trick to combating harmful algal blooms, not just in Grand Lake but across the state of Ohio, across the Midwest, across the planet, is getting these excess nutrients reduced."