Toledo's drinking water is once again safe, Mayor Michael Collins announced as he took a sip from a glass at a Monday morning news conference — but scientists say the harmful algal blooms at the heart of the water crisis are likely to persist well into the future given a confluence of shifting agricultural practices, invasive mussels, and global climate change.
"Here's to you, Toledo," Collins said at the conference, smiling for cameras before taking a sip of water drawn, presumably, from a nearby tap.
The water is likely to remain safe to drink for "a while," Gary Fahnenstiel, a research scientist with the University of Michigan's Water Center in Ann Arbor and an expert on harmful algal blooms, told NBC News.
Water managers have added more activated carbon to the water at the intake point in Lake Erie, and chlorine has been added to the system to help clean the water — strategies experts hope will keep the water safe, noted Jeff Reutter, director of Ohio Sea Grant at Ohio State University.
"The big concern on Lake Erie right now is that bloom that we've got is likely to persist," he told NBC News. "It will move from west to east. It is likely to persist well into October and it will probably peak in September, so it hasn't reached its worst yet. It is unfortunate that last Friday that bloom blew down by the wind right over top of the water intake for the city of Toledo. That was the unfortunate set of circumstances."
Blooms of the poisonous blue-green alga Microcystis and unhealthy concentrations of its toxin microcystin at the water intakes are related, but separate issues, according to Fahnenstiel, who led the Harmful Algal Bloom Program in the Great Lakes for the National Oceanic and Atmospheric Administration in Ann Arbor for 30 years before joining the University of Michigan.
"You have to have this mix of things to happen. It is kind of like a mini version of the perfect storm to have these big nasty blooms."
The blooms occur at the surface of the water while the intakes are located near the bottom of the lake. In Toledo, he said, the distance between the location of the blooms’ highest concentration and the water intake was 20 to 25 feet. This distance, he explained, is typically sufficient to dilute the toxin to levels that fail to trigger a health advisory.
"Something freak, or something unusual, happened to get it into the water intake," Fahnenstiel said. What exactly happened will be the subject of a state review. Regardless, the addition of activated carbon to the water intake should solve the drinking water issue.
But it may not be a lasting remedy, according to Reutter, who said it is "highly likely" that the winds could again blow the algal bloom over the top of the water intakes in Toledo. "I think it is also highly likely that it's going to happen at other places along the shoreline."
Agriculture, Mussels, and Climate
Harmful algal blooms are increasing in volume and frequency in western Lake Erie, according to Fahnenstiel, due to a confluence of three independent factors. First is an increase in the nutrient phosphorus flowing into the lake from farms, particularly in the Maumee River Basin. Phosphorus feeds the algae. The more phosphorus available, the bigger the blooms can get.
The amount of phosphorus going into the lake has risen every year since the mid-1990s. In addition to chemical fertilizers and manure on farms washing into the lake, researchers say sewage treatment plants, leaky septic tanks and stormwater drains contribute to the phosphorus problem.
"We can't just flip a switch and fix it, as the exact causes have not yet been identified."
An increase in invasive zebra and quagga mussels is the second major factor behind the increase in harmful algal blooms. While blooms are nothing new to the lake, Fahnenstiel explained, they have all been Microcystis for the past five to seven years. That's because the mussels eat the other algae, but filter out the Microcystis.
"The bottom line is the Lake Erie of today is not the same Lake Erie as in the 60s and 70s when we had algal blooms and problems," he said. "We have mussels driving the system."
Finally, climate change appears to be exacerbating the blooms. The frequency and intensity of storms followed by prolonged calm periods have increased in recent decades. These meteorological conditions are a perfect setup for the growth of blooms. The storms wash more phosphorous into the lake. They also mix up the water column, which suspends algae that settle in bottom sediments. Then, when the water is calm, the algae float to the surface and grow.
"You have to have this mix of things to happen," Fahnenstiel said. "It is kind of like a mini version of the perfect storm to have these big nasty blooms."
Control of the blooms comes down to control of the influx of phosphorus, he added. "We really can't control climate change and we really can't control mussels, they are already there. Your one controlling mechanism is phosphorus."
Farmers are aware of the need to control phosphorus, but say it will take time, according to Joe Cornely, a spokesman for the Ohio Farm Bureau. Area farmers in the 1980s switched to conservation tillage strategies to limit soil erosion, which at the time was a major concern. That worked, but "now we are in the 2014 timeframe and we're learning that those changes may be contributing to increased fertilizer nutrient runoff," he told NBC News.
To address the new problem, farmers have contributed $1 million to study the issue. Many farmers are investing in new fertilizer application technology that keeps more nutrients on the farm, and adhering to a nutrient management law designed to keep nutrients in place, Cornely said. But "we can't just flip a switch and fix it, as the exact causes have not yet been identified."
"We think farming practices are part of it," he noted. "We think that severe weather is another part. You know, you get a gully washer rain it is going to have a different effect on nutrients than if you get the standard light rains that we were accustomed to for the last 30 or 40 years. So, that is part of it as well."