At a Glance

First detected in 2012, cyanobacteria algae blooms have increasingly been reported in the lake.The unusual bloom has officials worried that this may become the norm as climate change and agricultural practicesalterconditions at the lake.

Ablue-green algae bloom described as "unprecedented" formed earlier this month along the shores of Lake Superior's Apostle Islands, prompting fearsthat climate change and human activities may make this the new norm on one of the world's fastest-warming lakes.

While algae inwaters surrounding the popular Wisconsintourist spot have since dissipated, the bloom tainted the lake's pristine blue waters with an unsightly, pea-green scum.

Robert Sterner, director of the Large Lakes Observatory at the University of Minnesota Duluth, told Minnesota Public Radio News that the sheer size of this particularbloom — an estimated 50-mile stretch of water was reportedly covered in algae — could make it "unprecedented."

“We believe it to be the ,” he told the New York Times. “I have been emphasizing we are talking about a small volume of Lake Superior, but it is a very highly prized, recreational part of the lake.”

First detected in 2012, algae blooms have increasingly been reported in the largest of North America's Great Lakes.

"They're very noticeable and very unexpected in a place like the deep and cold and generally low-nutrient Lake Superior," Sterner said.

Scientists suspect the blooms are developing for a number of reasons, most of them linked to climate change and human activities.

Like most freshwater cyanobacteria blooms, blue-green algae growth is triggered and fed by nutrient-rich runoff from cities and farmland. Agricultural practices have been under fire in recent years for the amount of phosphorus and nitrogen from fertilizers that are making their way into water systems.

Changing weather patterns as a result of climate change in the Midwest, particularly the increase in heavy rain-producing storms, seem to also behaving an impact on the blooms.

The 2012 bloomformed soon after 10 inches of rain fell on the Duluth, Wisconsin, area, resulting in a large runoff.

In 2016, storms that tributaries in northern Wisconsin triggered another bloom; and this year, nearly a foot of rain fell on the region in June prior to the development of the latest bloom.

"In each of those cases, we've seen a significant algal bloom develop," Brenda LaFrancois, a National Park Service aquatic ecologist, told MPR.

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Warming waters in Lake Superior are also suspected of playing a role in the development of blooms, which .

A 2015study by NASA and the National Science Foundation found that Lake Superior is one of the in the world. Summer surface temperatures on the lake have increased by 5 degrees Fahrenheit over the past 30 years, the researchers said.

The lake continues to warm at a rate of 2 degrees Fahrenheit per decade, three times the global average, according to the study.

While Sterner was hesitant to outright blame the bloom on warming temperatures, he noted that the changes occurring at the lake seem to indict climate change.

"So, we might be hitting some temperature threshold,” he told the Times. “Something out there has changed, and the one thing we know securely is that the lake is warming.”

While some cyanobacteria blooms can be toxic, it remains unclear whether this latest bloom contained harmful bacteria. Tests are underway to make that determination.

If ingested, water contaminated withtoxins found in blue-green algae can cause nausea, vomiting and, in severe cases, acute liver failure.

The Centers for Disease Control notes thatcan result in a rash. Some research indicates a link between long-term inhalation of toxic algae fumes and neurological disorders like Parkinson’s and Lou Gehrig’s diseases.