Blooming hell

Thanks to runaway development, toxic algae is killing local lakes again. Here's one way to stop it.

AS ANYONE WHO does it knows, scientific fieldwork can entail using the lowest and highest of technologies, often together. Today, on one of September's last achingly sunny golden afternoons, Jean Jacoby, an environmental engineering professor at Seattle University, and her grad student Berni Kenworthy employ two instruments as they hunt for toxic, pollutant-loving pseudo-algae in a Boston Whaler bobbing on Lake Sammamish, just off the mouth of Issaquah Creek. Kenworthy scans the screen on a Hydrolab Surveyor 4, a handheld computer that looks like a Game Boy on drugs, links by cable to an underwater sensor, and gives instant readings of temperature, dissolved oxygen, chlorophyll count, and a dozen other indices of water quality.

One thing the Hydrolab won't tell you—and this is still important, even in the digital age—is how murky the water is. For this, you need what Kenworthy calls "the most commonly used piece of limnological equipment"—limnology being the study of lakes and the equipment being a secchi disk, named after the 19th-century Jesuit astronomer who invented it. It's a saucer-sized disk on a calibrated line, marked in pie-slice quadrants like the nuclear hazard symbol. Its operation is simple: You play it out and note the depth at which you can no longer see it. Today, Kenworthy and I spot the disk nearly six meters down.

That's good news for the water today but bad for Jacoby and Kenworthy's project, and for the struggle to understand the dangers to Lake Sammamish and 80 to 100 other lakes in the developed parts of King County. The two are pursuing an ubiquitous but strangely elusive class of organisms called "blue-green algae," or, in science-speak, cyanobacteria: bacteria that carry on photosynthesis and otherwise behave like algae. Jacoby has an 18-month grant to monitor Lake Sam and try to figure out just what makes cyanobacteria grow, bloom, and, sometimes, pump out dangerous toxins. The impetus: a raging toxic algae bloom in summer 1997, when pets and people got sick after swimming in the lake.

Now the grant's about to end, and like a car that purrs when you take it to the mechanic, Lake Sammamish just won't provide a nice, nasty algal bloom. The last two summers have been notably lacking in the sunshine that algae thrive on. And the rains have been too steady; heavy downpour is best for washing down all the fertilizer, septic leakage, dog poop, and other phosphorus-rich nutrients on which cyanobacteria thrive.

But when the sun and floods return, the blooms likely will too. And the mild summer did not wear so lightly on all lakes. Seattle's shallow, uniquely vulnerable Green Lake turned greener and more viscous than pea soup as the algae bloomed with slimy abandon. Then, on August 24, scientists finally tested Green Lake water for cyanobacteria toxins for the first time.

JONATHON FRODGE, the King County limnologist who oversees the Lake Sammamish watershed, happens to live by Green Lake. Frodge already wondered what was incubating in his home waters. Finally, in August, the lake manager turned lake activist; he took a Green Lake sample to Jacoby and Kenworthy. They brought back bad news, which led city officials to close the lake to all recreation: The sample contained 30 times as much of the potent liver and nerve toxin microcystin, produced by a cyanobacterium called Microcystis, as the World Health Organization allows in drinking water.

And though Green Lake isn't supposed to be for drinking, uncounted dogs and splashing toddlers lap it up. So, unintentionally, do older swimmers. And you needn't drink microcystin to get sick from it; in Australia, soldiers ordered to jump into a blooming lake came out with blistered mouths, diarrhea, and pneumonia—a nastier case of the familiar "Green Lake crud." The bacteria often kills Midwestern livestock that drink from infected ponds and probably kills many people in China. It has been shown to promote tumors and cause liver failure. In 1996, 85 Brazilian dialysis patients got liver disease and 60 died after receiving cyanobacteria-tainted water.

Though last month marked the first time researchers checked for toxins in Green Lake, that surely wasn't the lake's first toxic bloom. Cyanobacteria have also been caught going toxic in Pine Lake on the Sammamish Plateau, Phantom Lake by Black Diamond, American and Steilacoom lakes near Tacoma, and poetic Lake Desire near Renton. The techniques for tracing algal toxins were unknown in the 1950s and '60s before the Eastside's sewage was diverted to Puget Sound, when algae turned Lake Washington into a fetid, fish-killing, swimmer-sickening cesspool. But the experts have little doubt that cyanobacteria went toxic there as well.

It was almost exactly two years ago that Lake Sammamish went toxic in a particularly nasty way. The way to measure toxicity in lake blooms (and in "red tides" produced by marine cyanobacteria) is the "mouse assay": inject crushed algae into mice and wait for the mice to die. Mice injected with 1999 Green Lake Microcystis lasted 24 hours. Mice dosed with the 1997 Sammamish vintage died in five minutes. "It was the worst bloom I've ever seen," says Frodge.

THE GREEN LAKE and Sammamish blooms put officials on alert; Seattle Parks resources manager Kevin Stoops says his department will resume monthly monitoring of Green Lake, which it ceased in 1997. (It won't test for toxins, which is more difficult.) But it's not clear how much city and state lake-tenders can do; the funds that were dedicated to lake protection in the 1980s and early '90s have dried up, and Frodge has given up chasing chimerical grants.

Jacoby isn't giving up, though. "Lakes are really important for recreation, aesthetics, and wildlife." (Salmon pass through them on their way to and from spawning streams, and some young salmon stay in lakes as they grow.) "They really are the most sensitive part of a watershed—the low spots, the sinks where everything drains. And as development continues around lakes, we'll see more impacts."

Already, Frodge and Jacoby see the dramatic improvements in lake water quality of the 1970s and '80s slipping into reverse. Fast-growing Eastside cities now claim the surplus drinking water Seattle used to use to flush out Green Lake. By mid-September, says parks manager Kevin Stoops, visibility in Green Lake was "the lowest I've ever seen"—a secchi reading of less than two feet. And conditions could get even worse as Green Lake—a "late stage" water body, with no regular inflow or outflow—continues its slow death.

Chuck Williams, a UW botanist studying algae, says Lake Washington recovered so fast and well because of its size and turbulence, which prevents cyanobacteria from blooming. "But in smaller lakes, once you've tilted the system, it's very hard to go back. It's a feedback effect. The cyanobacteria shade out everything else and prevent other organisms from growing."

Many people blame waterfowl, especially the strutting turd machines known as Canada geese, for pushing lakes to this living death. But Williams contends that "the geese have become scapegoats. Yes, they contribute nutrients [feces], but they aren't driving the problem. We had nutrient problems before we had geese. No one wants to talk about the big problem: what development does to lakes." Everything that humans stir up or dump upland eventually washes down. The insecticide used to kill the crane flies that sometimes chew up lawns goes on to kill the lake critters that eat algae. And using the herbicide Rotinone to kill floating milfoil gives algae a double boost: It eliminates a competitor and serves up a feast of dead weeds.

The lakes' best defense is forests, which slow run-off and take up nutrients—functions that the cul-de-sacs and parking lots that replace forests perform dismally. As a second natural line of defense, wetlands also trap nutrients. Vast marshes grew beside Green Lake and Lake Washington until the early 1900s, when Lake Washington was lowered with the opening of the Ship Canal and Green Lake was lowered to create the park. Wherever lake shores got developed, bulkheads, beaches, and fertilized lawns replaced the reeds and rushes. But might some wetlands be restored, to buffer the lakes once again?

Australia, the site of world's biggest toxic blooms (one in 1991 covered a 600-mile river system), thinks so; it rerouted one scummy river through an artificial wetland and, according to The Christian Science Monitor, got clear, swimmable water. Could King County do the same? "There is a lot of potential for doing that here," says county limnologist Frodge, who worked on the design of a celebrated wetland-cum-sewage-treatment plant in Arcata, California. He notes one caveat, however: "Since wetlands take up nutrients when they're growing and release them when they're not, you'd want to be able to turn them on and off"—that is, route run-off through them in the growing season and around them in winter.

Such a managed wetland would work with a concentrated water source, not with the diffuse run-off of thousands of lake-facing lawns. The state fisheries department, in collaboration with the county and city of Issaquah, already plans a model project on those lines: a greenhouse mini-wetland to clean up the effluent from the state's Issaquah Fish Hatchery, which now runs into Issaquah Creek and is the last phosphorus point source in the Sammamish basin. The main intent is to "introduce people to the idea of wastewater treatment and reuse," says county planner Kristie Silver, since the hatchery supplies less than 1 percent of all the lake's phosphorus.

Jonathan Frodge sees a bigger possibility: Build a wetland at the mouth of Issaquah Creek, where Jacoby and Kenworthy are trying to puzzle out the lake's mysteries. "Seventy percent of the nutrients in Lake Sammamish come from Issaquah Creek, whose watershed is experiencing significant development. Reestablishing the delta wetland would be one of the best ways to deal with the lake—because once the nutrients are in the lake, they're out of your hands."

 
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