It was summer in Toledo, and Lake Erie was pea green with a type of algae so toxic it could kill a dog. This was not unusual.

In fact, nearly every summer thick mats of toxic algae—known as harmful algal blooms (HABs)—emerge in the lake near Toledo. Winds tend to blow the blooms east toward deeper waters, breaking them apart and keeping the microscopic organisms confined to the lake.

But in August 2014, something unusual happened: Strong northern winds pinned a bloom against the shore—and in direct contact with intakes for the city’s water supply, which serves nearly a half-million people. Neurotoxins released by the algae entered offshore water intakes in such high levels that normal treatment processes failed to remove them below one part per billion, the cutoff at which the World Health Organization deems water unsafe.

Concerned that the toxin could end up in faucets and fountains in and around the Toledo metropolitan area, officials put out the call: Don’t drink or cook with the water. Doing so, people learned, could lead to vomiting and diarrhea, skin irritation, even liver damage. Boiling the water wouldn’t help, and could make it more toxic. Soon the National Guard was unloading bottled water from the back of trucks to the thirsty and frustrated, thousands of whom crossed state lines in a desperate bid to stock up, clearing shelves in stores up to 50 miles away.

“For the people of Toledo, this was a call to arms,” says Helen Domske (MS ’85), associate director of UB’s Great Lakes Program, which educates the public and policymakers about the lakes’ ecosystem.

Many strains of algae are beneficial to lakes, forming the base of intricate food webs. Other strains are harmful and can severely disrupt habitat, wildlife populations and the balance of ecosystems. Summer conditions in Lake Erie have become the perfect setting for a particularly toxic strain, known as Microcystis, to thrive and form blooms so large they’re visible from space.

Toxic algae in Lake Erie are particularly acute in the western basin around Toledo—where the waters are shallow, staid and pumped full of outside nutrients, primarily phosphorous and nitrogen, that help algae grow—but they are an increasing problem in inland lakes around the country and throughout the world. Their presence is largely a result of human activity: increasing fertilizer runoff from agriculture and raw sewage from wastewater plants, compounded by climate change.

Moreover, the impact of toxic algae blooms goes beyond the risk of a tainted water supply. Even when the water running from our taps is clean, toxic algae in the lake are outmuscling strains of good algae and expanding dead zones that affect fish populations and habitats. Algae also can wash up on public beaches and harbor the growth of salmonella and E. coli.

The threat is real, and multifaceted, and likely to worsen without significant changes to human habits.

“Lake Erie is dead” was a common phrase in the 1960s, when algae blooms contributed to a severe disruption of the lake’s ecosystem. In response, the U.S. spent $8 billion over the next two decades to improve wastewater treatment, and state and local laws reduced phosphates in laundry detergents; these steps significantly reduced levels of the minerals that fed toxic algae growth in the lake.

Lake Erie’s health noticeably improved: Wildlife returned, algae blooms became manageable or disappeared altogether, and recreation in the region, which had all but died in the 1960s, flourished into a multimillion-dollar industry by the ’90s. Lake Erie’s comeback was celebrated as one of the largest environmental cleanups ever seen and became a case study in reversing human-driven damage, says Joe Atkinson, a professor of environmental engineering at UB, and director of the Great Lakes Program. “Now,” he says, “the situation is trending the other way again.”

This time around, the brunt of the blame for outsized algae blooms is largely directed at farmers, who, in a chase for higher yields, have been accused of overloading their fields with fertilizers, such as manure, that naturally contain phosphorous and nitrogen. Farmers were not affected by state and local laws to reduce phosphates in common products, and they face few limits to the amount of fertilizer they can apply to their fields.

“It’s human nature,” says Domske. “We think: If one scoop is good, then two scoops must be better. That’s not necessarily so with fertilizer.”

To be fair, it’s not all the farmers’ fault. Other factors, which were not in play in the ’60s, are making our current toxic algae problem more complex—and more severe. One, says Atkinson, is climate change, which, in addition to trapping more heat in the lake (helping algae to grow), is causing more intense and frequent rains in northern Ohio. Heavy downpours pick up fertilizers from farms, lawns and golf courses and dump them into rivers; rivers discharge this runoff into the lake.

Meanwhile, surges of water from large storms periodically overwhelm smaller wastewater treatment plants, allowing untreated sewage to flow directly into the lake. Like fertilizer, urine and solid waste naturally contain phosphorous and nitrogen, providing a ready-made food supply for algae.

Muddying the waters even further are invasive species. Domske has been diving in Lake Erie for decades. Where plants and sand used to be, she now sees thick clumps of zebra and quagga mussels—invaders that were introduced to the lake in the late 1980s and mid-1990s, respectively. She has seen firsthand how these unwelcome critters aid algae blooms and threaten biodiversity.

Specifically, the mussels filter nutrients, use up oxygen and expel phosphorus as waste, increasing concentrations near the lakeshore where toxic algae thrive—and where water enters the public supply. Mussels also reject toxic algae as food, feasting instead on beneficial algae—removing competition to harmful algae for nutrients—and upsetting the base of the food chain.

Last fall, the EPA announced a billion-dollar strategy, called the Great Lakes Restoration Initiative (GLRI) Action Plan II. A holistic approach to improve the health of the entire Great Lakes system, the plan is funding state and local entities to clean 10 of the most polluted rivers and harbors in the system, restore habitat to protect native species, and encourage certain plant species to thrive in wetland areas now warmer because of climate change.

It’s the sequel to a 2010 plan that has spent $1.2 billion so far on more than 2,000 projects to restore coastlines, clean toxic areas and improve water quality. The new plan also establishes more holding tanks for the improvement of sewage treatment.

In the meantime, researchers at UB and elsewhere are doing their part to find solutions.

Atkinson is studying the movement and mixture of water in Lake Erie’s basins in an attempt to forecast weather conditions and prevent unnecessary runoff from entering waterways to begin with. “If we can better predict weather patterns to anticipate heavy rains, then it may be possible to convince farmers to apply fertilizers on different schedules,” he says. “Fertilizers absorbed by soil won’t be in our waters giving algae a free meal.”

In late 2014, the Ohio legislature considered the nation’s first ban on the application of fertilizer under conditions that could impact runoff: recent precipitation, when the ground is frozen, or when forecasts call for a half-inch or more of rain or snow. Though the measure was defeated, its supporters pledge to resurrect the bill in 2015.

On the wastewater side, UB chemistry professor Diana Aga also is looking to head off a problem at its source—in this case, by cutting down the amount of nitrogen waste heading to treatment facilities. Using funding from the EPA, she is helping to develop technology that treats human urine at the household level, diverting it from treatment plants and using it to fertilize crop fields.

“Urine separation at the source reduces the cost of treatment and the amount of nutrients that goes into the receiving surface waters,” says Aga, who also serves as a project leader of a seed grant from RENEW (Research and Education in eNergy, Environment and Water), a new interdisciplinary research institute at UB that was formed to address complex and urgent environmental issues.

Minimizing the flow of nutrients into the lakes from fertilizer and wastewater would not only reduce algae blooms, but also help alleviate some of their scarier side effects, like dead zones in the water and heightened bacteria levels on land.

When algae are allowed to thrive, decaying clumps from blooms wash up on beaches. According to a 2014 study co-authored by UB engineering master’s students Aubrey Beckinghausen and Alexia Martinez, these clumps shelter dangerous bacteria, like E. coli and salmonella, which are particularly threatening to children and the elderly. Dozens of Lake Erie beaches have posted warnings or have closed down to swimmers in recent years because of high levels of bacteria and toxins.

Dying algae that don’t wash ashore drift to the bottom of the lake, creating dead zones. Bacteria and fungi decompose the dead algae, consuming enormous amounts of oxygen in the process; lack of oxygen means bottom-dwelling fish and other wildlife cannot survive. While dead zones shift in location and size from year to year, they have been known to stretch across the central basin—Lake Erie’s largest area. Some years have seen severe reductions or shifts in habitat and wildlife that populate the lake’s cold bottom layer, upsetting the balance of the ecosystem throughout the lake, says Domske.

Dire as all this sounds, researchers are optimistic about the lakes’ future. “Natural lake processes can deal with many of these issues,” says Atkinson. “We just need to ease the pressure.”

This is especially true in Lake Erie, which holds the least volume of all the Great Lakes and can flush out completely in about 2.6 years. In contrast, Lake Michigan has a retention time of 99 years, while Lake Superior’s is 191 years.

“Since water is replenished frequently in Lake Erie, remediation efforts can be accomplished quicker,” says Domske. However, she adds, some of the newer problems facing the lakes are not reversible, like zebra mussels. “Killing [them] is not practical; each female can lay a million eggs. We are adapting to a new reality.”

And who might that “we” include? Approximately 37 million people live in the Great Lakes basin. More than 26 million rely on the lakes for drinking water. It begs the question: Could what happened in Toledo last summer happen in Buffalo? Chicago?

Given the colder, deeper waters near those cities, says Domske, it’s not likely—but not impossible. “Ultimately, it could depend on what we do next in the coming years,” she warns. “Continue down the same path, or make changes.”

While toxic algae threaten Lake Erie’s ecosystem and the public’s water supply, UB students are finding that some algae strains can be put to good use: as a source of sustainable biofuel, for example, or to aid in the cleanup of wastewater from the natural gas-extraction process known as hydrofracking.

Some algae strains produce lipids, or oils, that can be processed into gas, diesel or jet fuel. “The technology has been proven. We want to make it more cost effective on a larger scale,” says environmental engineering master’s student Mohsen Ghafari, who—finishing a study begun under former assistant professor of environmental engineering Berat Haznedaroglu—is looking at the effects of adding different nutrient concentrations to water where algae live to improve lipid production. The more lipids, the more potential for efficient biofuel production, he explains.

Meanwhile, Luke Scannell, an environmental engineering PhD student who also began his research under Haznedaroglu, is working with strains of algae to remediate wastewater from hydrofracking, which generates significant amounts of contaminated water that is difficult to treat. Several algal species are capable of removing metals and some carcinogenic substances from wastewater through natural processes.

In tests at UB, six species showed promise in purifying wastewater ponds that collect near gas wells. Using algae as a form of pretreatment for wastewater can reduce the costs and the amount of treatment needed for water to be reused.

“Creating a financial incentive never hurts to pave the way for technology that’s environmentally positive,” says Scannell.

Most harmful algal blooms (HABs) flourish when elevated levels of nitrogen and phosphorous are present. Urban and agricultural run-off as well as overflow from septic systems and other sources of wastewater drain into shallow, stagnant water, creating an environment for toxic algae to thrive. Zebra and quagga mussels selectively feed and filter out other algae, which further enables HABs to flourish.