Toxic algal blooms are growing out of control


On the Fourth of July last year, an hour after playing in the North Fork of the Virgin River in Utah’s Zion National Park, a healthy five-month-old husky puppy started seizing and then died. Local health officials determined that the dog, named Keanna, had swallowed toxic algae from the river.

The Park Service warned against all forms of recreation on the North Fork for the rest of the summer because of the danger, effectively closing one of the most popular attractions in one of the country’s most visited national parks. Zion is just one of hundreds of popular places across the U.S. to have been impacted by toxic algae, which thrive in hot weather. This year, rivers and reservoirs across Utah are seeing unprecedented algal growth once again (the North Fork of the Virgin River is still under a warning advisory), while algal blooms continue to close bodies of water from Washington to Florida (a total of 278 were deemed off-limits in 2020). Officials in California are even investigating algae as a cause of a family’s respiratory death near Yosemite.

A report from the nonprofit Environmental Working Group, which tracked outbreaks between May and October of 2020, found documented cases of toxic algae in every state except Alaska. Last year more than 400 cases were reported, up from fewer than 100 cases in 2010, when the EWG first started keeping track. By July of 2021, the organization had seen a 46 percent increase in reports of blooms compared to the same period last year.

So what is toxic or blue-green alga? It’s a kind of naturally occurring microscopic cyanobacteria. If there are nutrients in water, particularly phosphorus and nitrogen, when that water warms up, the bacteria begin multiplying like crazy, creating algal blooms. And that’s when things can get really complicated.

When the bacteria blooms, it can emit thousands of different kinds of toxins, including saxitoxin, which causes paralysis, and the liver toxin and carcinogen microcystin. For humans, reactions can range from rashes, diarrhea, and sore throats to cardiac arrhythmia. Researchers are just starting to dig into the long-term health effects—it’s been linked to cancer, Alzheimer’s disease, and other neurodegenerative conditions. “The scariest part is that it’s really hard to predict toxins—you can’t tell if they’re toxic by looking at them, so you can’t just avoid them, and we don’t understand what triggers a bloom to be toxic,” says Anne Schechinger, senior economic analyst at the EWG. “We’re really at the beginning of the science.”

While we don’t know exactly what triggers the alga to release specific toxins, we do know what causes it to bloom and why it’s getting worse. “These blooms wouldn’t occur without phosphorus and nitrogen, which are mainly caused by fertilizer and animal-manure runoff, along with an urban area’s stormwater runoff and septic,” says Schechinger.

Commercial agriculture—both animal ag, which releases phosphorus in the form of manure, and crops, which use nitrogen as fertilizer—has increased the amount of those nutrients in the ecosystem to the degree that the Environmental Protection Agency called it “one of America’s most widespread, costly, and challenging environmental problems.”

Toxic algal blooms have also been exacerbated by climate change. Algae need heat and light to bloom, and rising water and air temperatures caused by a warming climate provide fuel. Heavy precipitation often makes things worse, and because of climate change, intense weather events are happening more often. According to a report from the EPA’s Office of Water, “Recent research suggests that the impacts of climate change may promote the growth and dominance of harmful algal blooms through a variety of mechanisms including: warmer water temperatures, changes in salinity, increases in atmospheric carbon dioxide concentrations, changes in rainfall patterns, intensifying of coastal upwelling, and sea level rise.”

That’s not good news for waterside communities, where an outbreak can affect people’s health and crush their livelihoods. This summer in Florida, both coastal and lakeside towns have had to close their water access after blooms caused huge fish die-offs and sickened beachgoers. “For a lot of towns that rely on bodies of water for their economy, this can be really really harmful,” Schechinger says. “The Mississippi Gulf Coast had a big bloom last year that shut down most of the beaches, and that had a huge impact on tourism.”

But despite these impacts, there’s no national oversight for outbreaks, and according to Schechinger, monitoring and management at the state level is highly variable. (The EWG uses local news reports to identify outbreaks, which means they’re probably undercounting.) The 1998 Harmful Algal Bloom and Hypoxia Research and Control Act split the responsibility on the federal level between the EPA, which monitors fresh water, and NOAA, which has started to track blooms in marine ecosystems, but no one is looking at the whole picture.

Plus, it’s not easy to track and regulate diffuse pollution that becomes dangerous as it accumulates. In the U.S., we address water pollution through laws like the Clean Water Act, which only covers pollution that comes from a single source, such as wastewater or industrial dumping. The impacts of toxic algal blooms are far removed from the source. For instance, the headwaters of the Virgin River in Utah aren’t particularly close to concentrated agriculture, and they’re far from urban septic systems, but nitrogen and phosphorus still build up in water as they wash downstream.

According to Schechinger, the only recourse is to rely on voluntary conservation to curb non-point-source pollution, which isn’t a very powerful tool. She says it would be much more effective to deal with it where it’s created, because it’s expensive and incredibly hard to clean up once it’s released. The economic cost of algal blooms amounts to an estimated $2.2 billion each year, and that number will grow as the blooms do.

For now, dogs are dying and you can’t go swimming or canyoneering in a growing number of places. And (welcome to 2021) the people bearing the brunt of the problem are not the ones responsible for its spread, and it’s only going to get worse.

One silver lining is that more people are starting to pay attention—NOAA, for example, just began making harmful-algal-bloom forecasts for the Gulf Coast of Florida and the Gulf of Maine, and it’s planning to expand into more places, including the Pacific Northwest, soon. Schechinger also points out that satellite mapping is getting better, so it’s becoming easier to trace pollution plumes to their source. And some regulation is getting passed on the local level: in Minnesota, where Schechinger lives, a new law just went into effect that mandates barriers between farms and major waterways.

The best thing for individuals to do is to start local and be loud. If you see something that looks like alga at your local beach or creek, report it to your health or water department. The more data points there are, the fewer people are inadvertently impacted, and the more powerful the argument for regulation becomes., 26 August 2021