An algae bloom in Utah Lake. (Rick Egan/Salt Lake Tribune via AP)

It is the summer of algae.

Across the United States, bodies of water teem with microscopic organisms, warmed by the sun and growing fat on stirred-up nutrients. Such microscopic explosions, called blooms, come at the expense of nearly everything else in the contaminated rivers and lakes. Their shores sport colors better suited to Gatorade factory rejects. What was once crystal or blue becomes scummy browns or dull reds — and, perhaps most significantly, a noxious snotty green. In places, the microbes are so numerous the water thickens to a soup.

Nor is it a problem unique to the United States. An expanse of Australia’s longest river in the Murray-Darling Basin has gone green with increasing frequency. The most recent bloom covered more than a 600-mile stretch.

“It’s been 40 years between blooms and then all of a sudden we’ve had five in 13 years,” Darren Baldwin, an environmental scientist for Australia’s Commonwealth Scientific and Industrial Research Organization, told The Washington Post by phone.

Utah Lake, a freshwater lake that covers some 150 square miles — one of the largest lakes in the Western states — has been drenched in cyanobacteria, also known as blue-green algae. The bacterial cell counts reached the tens of millions per milliliter, according to the Salt Lake Tribune. Two years prior, a cyanobacteria bloom that was toxic enough to kill two dogs was far less concentrated, numbering in the hundreds of thousands of cells per milliliter.

And then there is the stench.

A devastating toxic algae bloom turned the waters of Utah Lake green and have sickened more than 100 people. A timelapse shows the bloom swiftly overtake the lake in early July, and it has since spread to a nearby river that provides water to local farms. (Utah State Parks)

“It smells like something is rotting,” said Jason Garrett, Utah County Health Department’s water quality director, to the Associated Press on Friday. “We don’t have an idea of how long this event will last.”

Utah Lake is not a reservoir for drinking water. The scum nevertheless sickened swimmers, fishermen and others who came in contact with the bacteria. The Utah Poison Control reported 130 cases of skin rashes, vomiting and diarrhea, according to the Associated Press.

In Idaho, the state’s environmental quality department warned of blue-green algae spikes in Hells Canyon Dam. Exactly why blue-green algae produce toxins is a bit of a mystery. Better understood is that the chemicals can cause liver and skin damage in mammals. Human deaths from cyanobacteria are rare, though evidence of neurological effects is mounting. Dogs that slurp up water more frequently die from cyanobacteria. But the majority of deaths likely go unmourned, of fish and other organisms that suffocate as the bacteria suck the oxygen out of the water.

To the east of the Mississippi, an algae bloom wrapped around Florida’s coast. The scum put four counties in an avocado-hued chokehold in June, as The Washington Post reported previously. Eight manatees were found dead in the area. Though the cause of the manatee fatalities has not been confirmed, their stomachs — usually stuffed with seaweed — were found full of algae.

Because the Centers for Disease Control and Prevention launched the first reporting system for algal blooms in June, it is difficult to say with certainty if blue-green algae have spiked. Evidence, the agency says, is mounting. State officials have warned the public to avoid a pond in Rhode Island, a bay in North Carolina and a lake in California.

In an another light, it has always been the summer of algae blooms.

The organisms known as phytoplankton — algae, diatoms, cyanobacteria — are all variations on a microscopic theme. To live, they take in sunlight, carbon dioxide and nitrogen.

Such a diet seems odd to us. To cyanobacteria, our newfangled, mouth-breathing ways would seem strange. This planet belonged to thick mats of phytoplankton first. The Earth is about 4.5 billion years old. The oldest fossils of cyanobacteria — some of the oldest fossils in the fossil record — are 2.9 billion years old.

In the record of human history, algae blooms are not a modern phenomenon. In one scientific interpretation of the Revelation of St. John the Divine, when the ocean becomes “as the blood of a dead man” that was due to a reddish algae. Native Americans steered clear of water that glowed, as the New York Times reported. Later, that glow would be traced to dinoflagellates, a toxic type of bioluminescent algae.

It was not until the mid-20th century when researchers first caught wind of an unusual uptick in algae blooms. By the 1970s, blooms were a rare nuisance. In the summer of 1976, a sea bloom emptied Garden State fishermen’s nets after it killed lobsters, fluke and other marine bottom-dwellers.

What was the odd nuisance then took a deadlier turn for marine mammals in the 1990s, with reports like nearly 200 dead dolphins washing ashore in Mexico. Gangs were first blamed for chemical dumping, as The Washington Post reported, though the actual killer turned out to be algae.

“Twenty years ago, these kinds of outbreaks were rare,” said Nancy Foster, a marine mammal biologist and director of the National Oceanic and Atmospheric Administration’s national oceans service. “When we did see them, they were smaller in scale. Now they’re all around the coast, and almost every state is vulnerable.” That was in 1997.

In 2005, a red tide slimed California’s coast, leaving surfers with burnt eyes and rust-colored wetsuits. When it was Cleveland’s turn half a decade later, it was blue-green algae returning to Lake Erie after a long blooming absence.

Scientists are attempting to explain why blue-green algae is back with such a vengeance. A suspect, emerging in reviews like those published recently in the journals of Harmful Algae or Water Research, has been climate change.

It is a combination of both direct and indirect effects of climate change, Baldwin told The Post. “We’ve primed the system perfectly for blue-green algae blooms.”

The algae bloom after severe storms, which dredge up nutrients normally trapped at the bottom of lakes and rivers. (June 2016 was the hottest June on record, and boasted several massive thunderstorms.)

The algae bloom in hot heat and high solar radiation — unlike other microbes, they have the ability to adjust where they sit in the water column. (“Too much light, and they can’t photosynthesize,” Baldwin pointed out. Where other algae die, the blue-green bacteria motor downward.)

The algae bloom in water that is stagnant and shallow, which may describe many bodies of water in drought-sapped areas.

So the summer of 2017 may be a summer of algae, too. Blooms are “really hard to predict,” Baldwin said. But “it would be fair to say the incidence of these blue-green algal blooms will become more common.”

What blooms are not, Baldwin said, are inevitable. Managing the amount of irrigation, as part of a broader adaptation to climate change, has the added bonus of combating toxic blooms.

“If this is the new normal,” he said, “then we’re going to have to start thinking about how we regulate these systems.”