It’s a Godless 90 degrees. You’ve escaped the inferno of your non-airconditioned apartment and high-tailed it to Madison Beach. The dock is waiting for you to jump off of it into the cool of Lake Washington. You even waited 30 minutes after eating. But there’s a problem: The beach is closed. The water is full of shit. Welcome to hell.

All summer, beaches in King County shut down due to bacteria and toxins in the water.

The issue isn’t with the water quality in the county’s big lakes as a whole, but with certain shorelines (and a few smaller lakes). The bacteria and toxins fluctuate day to day, which is why, while the county’s maps of closed beaches are looking fairly green right now i.e. clean and safe to swim, in time your favorite beach could be bacteria riddled too.

If it seems like there are more beach closures these days than there were when grunge reigned supreme, it’s because there are. And it’s not because the water is getting grodier, or solely because our favorite boogeyman, climate change, is up to his old tricks. It’s science and a cross-departmental collaboration in King County keeping you from swimming a pool of goose shit in blissful ignorance.

King County teams are gathering more water samples from swim beaches than they did in the past. Each week, they evaluate the levels of poop bacteria and algae in the water to make the best safety call.

So,  blame the science if you can’t swim at your favorite lake. Thank the science if you don’t contract e.coli on a swim or  your dog doesn’t keel over and die after gulping down that sweet, sweet tainted water. And, it’s not going anywhere thanks to sturdy funding mechanisms that are resilient to autocratic anti-science budget cuts.

There’s Something In the Water (Poop)

The Cedar River, one of Seattle’s main sources for drinking water, feeds into Lake Washington. So does Issaquah Creek (we do not drink from this). Both fresh water sources are naturally filtered by the intricate root systems of forested land (thanks, trees!). Out in the open water, Lake Washington is fresh and clean. It’s the shores—and smaller lakes around the county—where things get dirty.

Daniel Nidzgorski, an ecologist at the King County Department of Natural Resources and Parks, says high levels of bacteria are responsible for most summer beach closures, fancy science talk for poop in the water.

”Poop can carry many different germs that can make people sick,” he says. “And so most of what we're dealing with is goose poop.”

It’s a fecal matter frenzy, especially in our waterways after a summer rainstorm washes goose slop into the water. Within all that dookie lurks e.coli, one of bacteria responsible for food poisoning.

Poop is mostly bacteria, not what’s left of a meal: 50% to 80% of it is the bacteria that lived in the intestine before nature called. One of the more dangerous intestine-dwellers is e.coli, the culprit behind many a lettuce recall and the reason we wash our hands after going number two. Some strains cause diarrhea and vomiting. When we swim in poop, we can ingest the bacteria. It can also irritate our eyes and skin.

A Blue-Green Bacteria Machine

Poop is not the only toxin scientists monitor. They’re on the hunt for toxic algae. Cyanobacteria, a photosynthesizing, sunlight gobbling bacteria, makes the blue-green variety of algae. Under certain conditions, the cyanobacteria population explodes, creating algal blooms that kind of look like the inky cloud from a scared octopus. Scientists aren’t totally sure why certain blooms turn toxic, but know it has to do with the cyanobacteria. Nidzgorski says it’s like a switch flips.

Algae thrives in excessively warm, nutrient rich lakes. The risk of a toxic cyanobacterial bloom increases when levels of phosphorus and nitrogen are too high.

Phosphorus, a key nutrient necessary for life on earth, is everywhere on our little planet.

Found naturally in the Earth’s crust, in soil, in the components of our own genetic code, phosphorus seeps into our waterways as things break down: eroded rocks leach phosphorus, decomposing plants and animals leave behind the phosphorus that made life possible. Water picks up traces of it and as it goes through the water cycle (surely you’ve heard of it) falls as phosphorus-rich rain.

It becomes a problem when humans disrupt the natural order. 

Rob Zisette, an aquatic science consultant at Herrera Environmental Consultants, says most lakes receive excess phosphorus through stormwater runoff

“Fertilizers, and all the stuff in the watershed that runs off the pavement… gets into the lake,” Zisette says. That includes unscooped dog poop and decomposing leaves.

Washington has tried to mitigate our impact. In 2011, the state passed the “Clean Fertilizers, Healthier Lakes and Rivers” bill to limit the amount of phosphorus in commercial fertilizers and household detergents, but phosphorus still infiltrates our waterways.

Green Lake’s Phosphorus Problem

Zisette’s main focus is Green Lake. The shallow north Seattle lake has a reputation for being unsafe to swim in. The rumor is based in truth.

Green Lake is what’s known as a eutrophic lake, which is low in oxygen, but overrich in nutrients like nitrogen and phosphorus that propel algae growth, mostly of the blue-green variety that can become toxic.

In summer, warm water and sunlight catalyze the bacteria in the phosphorus-rich lake sediment to eat up all the organic matter. Complicated oxygen-cycle science occurs and releases free phosphorus into the water, which acts as fuel for the algae and algal blooms that have plagued the lake since at least 1916. And because of climate change, summers are coming earlier. The county closed Green Lake this June after finding high levels of toxins. Right before we published this piece, the county closed Green Lake’s west beach.

All this algae and phosphorus is not unique to Green Lake, but it's certainly a problem.

Zisette has been dealing with it since 1991 when grunge really did reign supreme and, much less famously, the city paid for Green Lake’s first “alum” treatment.

“Alum” treatments are two part: Acidic aluminum sulfate neutralizes phosphates. The (chemically speaking) basic sodium aluminate prevents the water from turning too acidic. Zisette first dumped a fuck ton into the lake back in the 90s. But not enough. Their calculations were off. It’s a long story, he says.

A classic excuse. Then, more than a decade later in 2004, with better calculations and technology, Zisette administered another alum treatment in Green Lake.

“We put in a whopper dose, three times that 1991 amount,” Zisette says.

Zisette, who (for all of our benefits) keeps putting this shit in the lake, also oversaw the most recent Green Lake alum treatment in 2016. It didn’t go quite as hard. To put it into perspective, the “small treatment” in 2016 used over 81,700 gallons of alum and took six 12-hour days of a boat criss-crossing the lake to complete. It still did the trick. Green Lake turned blue.

No matter how much alum Zisette dumps into Green Lake, it’ll always be a temporary fix. They only last about 10 years. Zisette’s research found most of Green Lake’s phosphorus is in its sediment. But rainfall, bird poop, decaying lake plants, and stormwater runoff from Woodland Park and off Aurora Avenue are always adding more.

But we don’t know all the ways phosphorus is getting in, Zisette says. That study would take a year and a lot of money to complete.

Green Lake is due for another visit with Dr. Alum and nurse sodium aluminate, but it's not in a dire state, Zisette says. Whatever timeline Zisette works out with the city, the treatment itself will likely be smaller due to a thinner city budget.

Meanwhile, he’ll still go swimming in Green Lake.

Shit Worth Doing Science About

Whether it's poop bacteria or the toxic algae in the water, the impact on swimmers is the same, the county says: nausea, cramps, and diarrhea.

An A-team of Public Health-Seattle & King County, King County Environmental Lab, King County’s Department of Natural Resources and Parks, and other local jurisdictions don’t want you in the gross, poopy water, so they’re testing all swimming shores weekly. But it’s not like nuclear waste. Or, the devil.

“It's not like, ‘Oh my god, I touched the water. I'm gonna die,’ Nidzgorski, who is part of that team,  says. “It's just higher than public health thinks is a good trade off.”

This testing is new. Seattle only started testing water quality in 1996 after the City Council and Seattle-King County Department of Public Health decided to investigate the poop pollution—yes, human poop—from boats in Lake Washington, says Nidzgorski. That initial program only tackled high-boat traffic areas like Lake Washington. Eventually, testing expanded to give us what we have today.

Scientists only started testing for toxic algae in 2005, according to Rachel Gravon, a water quality planner at King County Department of Natural Resources & Parks. It first popped up around Puget Sound in 1989, and the problem grew in the 1990s. In 1997, we had our first dog death. A golden retriever named Maggie died after swimming in Lake Sammamish.

Swimming in tainted water is more dangerous for dogs than people. They swallow more as they swim, thus ingesting more toxins. The scummy dip that gives a person a “tummy bug,” as Nidzgorski says, can kill a dog like Maggie (RIP). The Oregon Health Authority actually has dog guidance. Public Health-Seattle & King County doesn’t despite the fact that there are more dogs than children here.

Nidzgorski says there’s no guidance because dogs aren’t supposed to swim here. But dogs can’t read, and based on the number of dogs swimming in the lake, neither can many of their owners.

“Dogs aren’t supposed to swim in the lake, but they do,” Zisette, the aquatic consultant, says. “And so I worry for dogs, because they drink water that is yucky.”

With so many dogs here (and rule breakers likely unaware of the deadly consequences) the county should have a dog scale!

Scientists with the swim beach sampling program collect and analyze around 1,600 annually. The science keeps improving. In 2019, county scientists started taking three samples at each beach instead of one. But multiple samples also meant more data. More data increased accuracy. Accuracy resulted in more beach closures.

“That doesn't necessarily mean the water quality has changed,” Nidzgorski says. “It's really that we started doing better science.”

To test the water at each beach, scientists dunk three bottles for bacteria and one for algae beneath the surface at all sides of a swimming area. Back at the lab, scientists filter the sample for the bacteria, mix them with an agar, and grow them on petri dishes, which become a little colony they can examine under a low power magnifying glass. At a certain temperature, the bad bacteria turns purple.

Swim advisories are guidelines, not rules. Scour any open water swim group on Facebook and you’ll find hemming and hawing about whether to swim at a closed beach. Nidzgorski, a scientist, says it’s best to avoid areas with high-bacteria levels and find a safer, clear place to swim at this county website. Or, to be patient. Over the last five years, 16 out of the 28 beaches monitored had low bacteria levels more than 95% of the time, he says.

To swim or not to swim is ultimately a personal choice, but the county would rather keep you safe than have you vomiting all over the place and/or killing your dog.

Editor's note: This article has been updated since its original publication. We misstated that the county's scientists examine bacterial samples from lake water under a microscope. They, in fact, use a low power magnifying glass.