COLUMBUS, Ohio (WCMH) – It’s a yearly occurrence along Ohio’s northern shoreline: expansive masses of algae turn Lake Erie’s usual indigo color to a crude green, as if there had been an oil spill of pea soup.

Some are just a nuisance, some are paralyzing threats to health, wildlife and tourism, but experts anticipate that algal blooms will increase as climate change brings warmer temperatures and stronger storms to Ohio.

How algal blooms form

Algal blooms appear in Lake Erie every summer, especially in the shallow west where rivers meet the lake at Toledo, Port Clinton and Sandusky.

Eighty-five percent of land in the Western Lake Erie Basin is used for agriculture, and the water that flows from land to lake, particularly during spring rains, picks up chemicals like phosphorus and nitrogen used in field fertilizer.

When these nutrients in farm runoff reach Lake Erie, microscopic organisms already in the lake called blue-green algae (officially “cyanobacteria”) feed on them. The more nutrients in the runoff, the more cyanobacteria can bloom with sunlight.

2014 Lake Erie Toledo algae algal bloom water glass
In this Aug. 3, 2014 photo, a sample glass of Lake Erie water is photographed near the City of Toledo water intake crib, in Lake Erie, about 2.5 miles off the shore of Curtice, Ohio. (AP Photo/Haraz N. Ghanbari, File)

During an algal bloom, the cyanobacteria settle into a green muck just under the lake surface. When they die, their decomposition steals oxygen from the water. That kills fish – hurting recreation and the economy – and it pollutes drinking water.

Some blooms get so bad that the cyanobacteria get toxic. In August 2014, Toledo shut off its water supply for nearly three days, leaving more than 400,000 people without clean drinking water, because a bloom produced too much of a toxin called microcystin.

Toledo water crisis 2014
Megan Anllo, a volleyball coach at at Woodward High School, carries a bag of water to a nearby car, Sunday, Aug. 3, 2014, in Toledo, Ohio. (AP Photo/Haraz N. Ghanbari)

Warmer water a better breeding ground

“Cyanobacteria are smart,” said Hans Paerl, a professor of marine and environmental sciences at the University of North Carolina. “They’ve been around for a long time, over 2 billion years. And clearly, they’re taking advantage of what we’re here doing in the (Lake Erie) watershed, but also other things that are going on, including climate change.”

Paerl, who has been studying blooms in western Lake Erie with researchers that include Bowling Green State University, presented Wednesday to more than 1,000 attendees in a virtual conference hosted annually by The Ohio State University.

He laid out a climate change-fueled, one-two punch that could increase blooms: warmer temperatures and stronger storms.

Blue-green algae “like it hot,” Paerl said, and Lake Erie – the shallowest and thus warmest Great Lake – is especially susceptible. But water temperatures in the lake are increasing, which means ice forms later and melts earlier, giving blooms more time to grow.

“It looks like the blooms are starting earlier and they’re lasting longer,” Paerl said. “And that clearly is linked to climate change, or at least warming. And because of that, western Lake Erie has experienced a one- to two-day increase in growing days per year since 2002.”

That also means the risk increases for toxic blooms that keep anglers and charter boats off the lake and force water supply shutoffs, like what happened in Toledo in 2014.

Warmer lake water also increases stratification, a thermal separation of the lake into layers, allowing algae – which thrive in warm water – to stay in the lake’s warmer surface layer.

More rain means more runoff

With warmer waters giving cyanobacteria more time to grow, another effect of climate change could bring them more nutrients to bloom: more rainfall.

Air temperatures have warmed over Ohio, allowing local weather patterns to hold more moisture. The average spring temperature recorded at Toledo Express Airport has risen 2.7 degrees Fahrenheit since 1970, according to researchers at Climate Central, and the average summer temperature has risen 3.4 degrees.

This past summer – June through August – was the second-warmest in 149 years of recordkeeping, as was 2020 the second-warmest year there. As for rainfall, four of Toledo’s eight wettest years have been since 2006.

“Storms are getting more intense, more extensive and more frequent,” Paerl said, alluding to a trend of more storms forming in the Atlantic Ocean and hurricanes strengthening more before they reach landfall.

NBC4 reported last week how stronger hurricanes mean more rain in Ohio, after Hurricane Ida’s remnants caused flooding around Columbus. That system did not reach the western half of Ohio, but it’s not farfetched to imagine future, intensified hurricane remnants hitting that bloom-prone region with rainfall and floods.

“Clearly, more rains lead to more nutrient inputs” into runoff and Lake Erie, Paerl said.

State program tackling problem

A multi-agency initiative started by the DeWine administration is already working to curb algal blooms, targeting the source of the problem: farm runoff.

“We’re trying to reduce the overall nutrient losses from cropland by focusing in on three areas,” said Terry Mescher, H2Ohio program manager for the Ohio Department of Agriculture.

ODA’s main area is nutrient management, contracting with farmers to decide what fertilizers to use and how much, basically deciding the best ways to apply phosphorus- and nitrogen-rich commercial fertilizers, livestock manure and/or biosolids from a wastewater facility.

That includes looking at when to fertilize, Mescher said, like “during the late summer, early fall months, when our overall chances of runoff are less.” For example, research shows putting fertilizer nutrients directly into the ground instead of spreading them can “significantly reduce phosphorus losses.”

ODA also works on soil erosion management, which includes incentivizing corn and soybean farmers to plant a cover crop in the winter like wheat instead of having a bare field; and water management, like improving field drainage.

While ODA works with farmers to implement its programs, the Ohio Department of Natural Resources restores and enhances wetlands to buffer runoff, and the Ohio EPA improves water infrastructure.

‘Overwhelming’ interest from farmers

Local soil and water conservation districts handle H2Ohio applications and discus practices with farmers, who then sign three-year contracts with ODA to implement those practices. After a farmer holds up their end of the deal, the district verifies the land and ODA pays the farmer.

The ag department has committed $125 million for farmers in the program’s first 14 counties in Northwest Ohio, and it plans to commit up to another $78 million more for farmers in 10 counties added in July.

H2Ohio 10 county expansion
(Screenshot via H2Ohio fiscal year 2021 report)

“For this first year, over 1,800 producers have signed a contract to implement these H2Ohio practices,” Mescher said, including 1,600 nutrient management plans among 900,000 acres of cropland. Adding signups from the 10 new counties, H2Ohio acreage is up to 1.1 million acres.

“The interest in the program has overwhelmed ODA’s expectations,” Mescher said, which was just 150-200,000 acres.

Climate connection

H2Ohio does not focus on how climate change may increase runoff and algal blooms, a spokesperson said, but Mescher connected the program’s efforts with rainier springs.

“The size of the bloom in general is pretty much controlled by the nutrient load that comes into Lake Erie from March to early July,” he said.

In 2011, for example, near-record spring rainfall in Northwest Ohio (second-most recorded at Toledo Express Airport) caused a record shattering algal bloom with a peak intensity more than three times greater than any previous bloom.

“As we have wetter springs and more rainfall, more intense rainfall in the springs,” Mescher said, “that tends to increase the loads.”

H2Ohio has funding through 2023, since the latest state budget only goes out that far. But Mescher hopes there will be a “version 2.0” for 2024 through 2026.

“We’re starting these discussions now,” he said.