With the water ban lifted, more than 400,000 people in the Toledo, Ohio, area are once again able to turn on their taps. But the bloom of toxic algae in Lake Erie isn’t going away anytime soon, and the troublesome scum serves as a warning that one of the largest supplies of fresh water in the United States is in trouble.
“These blooms are not going to be eradicated in the short term,” says Timothy Davis, a researcher at NOAA’s Great Lakes Environmental Research Laboratory in Ann Arbor, Michigan. “They are a symptom of a larger problem: a lot of our lakes are sick, and so you get these harmful events occurring.”
Blooms of the toxic algae Microcystis are fed by phosphorus running into the Great Lakes from nearby farms, which use the nutrient as fertilizer. The algal menace has been popping up every year in the western basin of Lake Erie since the early 2000s.
The blooms have been getting worse in the past few years thanks to three main influences, says Gary Fahnenstiel, a researcher at the Graham Sustainability Institute at the University of Michigan:
- Warmer average temperatures in the lake mean longer growing seasons for algae and bigger, more persistent blooms.
- Climate change has also increased the intensity of regional storms, and heavier rains wash more phosphorus from the fields into the lake.
- Zebra and quagga mussels native to Eastern Europe found their way into Lake Erie via ballast water from cargo boats. These mussels feed on phytoplankton, but they reject the toxic Microcystis, while excreting nutrients that fuel the growth of the bad algae. This has created an ecosystem where the toxic terrors can thrive at higher concentrations than they otherwise would.
Despite the severity of recent blooms, Toledo’s water troubles this month can be mostly attributed to bad luck, Fahnenstiel says.
“Other water intakes in the western basin had no problems during this crisis,” he says. “Toledo just happened to have algae congregate near the intake pipes, and I’m not sure why. There is something unique here that allowed them to have a water issue.”
Unusually high winds – another effect of climate change -- are the most likely culprit, Davis says. Normally the algae float on the surface of the water, suspended several feet above the intake pipes that send drinking water to nearby towns. But winds can churn the water and mix algae deeper into the lake.
“We had high winds out of the north that drove the bloom to the south shore, and algae congregated around the water intake,” he says. Water treatment facilities can remove some of the algae from water being piped in, and then can filter out any remaining toxin with activated carbon, Davis says. In Toledo’s case, the amount of algae that reached the intake pipes caught water managers off guard, and they probably did not use enough carbon to handle the load.
The water ban was unusual. But if the blooms are not eradicated, such events may become more regular occurrences in Toledo and other cities that draw fresh water from the basin, says Carol Stepien, director of the Lake Erie Center at the University of Toledo.
Last September, an especially bad bloom forced officials to enact a water ban in Carroll Township, to the east of Toledo, that affected about 2,000 people. And with this year’s bloom predicted to be severe, Stepien thinks the situation is ripe to repeat in the coming weeks.
“We’re not even in the peak of the bloom season yet. That usually happens around the end of August to mid-September. So I would expect this will happen again,” she says.
Things could get even more dire in future years, Davis says: “Right now, scientists are predicting that warmer temperatures and more nutrient loading will cause blooms of greater size and greater toxicity that last longer.” That’s why several projects are already under way to help control pollution while still maintaining local agriculture and supporting farmers, he says.
“We’re trying to use high-tech systems, like being able to scan fields with satellite imagery to see where the ground is already saturated with nutrients, so farmers can only use the levels of fertilizer they need,” Davis says.
Aside from the risks to drinking water, surface algae can still be a danger to pets and to recreational swimmers, making the blooms a critical issue for any affected waterway, including the Chesapeake Bay and the Gulf of Mexico, Stepien added.
“I’m looking out my window now and the lake is very pretty,” she says. “But when I get up close I can see the greenish tinge. We need stricter regulations, enforcement, and more research dollars. We’ve known exactly what we need to do for some time, and we need to do it now.”
While he believes the water ban in Toledo was a one-off event, Fahnenstiel thinks the extreme situation could spur action to clean up the basin and better manage runoff.
“It typically takes a crisis to get people to do things. This may be the crisis that will help stimulate movement to control phosphorus in the basin,” he says.