THE GORGE — Historically, photosynthesizing algae and microbiota have largely been benevolent, producing oxygen and creating the atmospheric conditions to support complex, mammalian life. As humans have altered the environment, however, one particular type is playing an increasingly opposite role.
Cyanobacteria, otherwise known as blue-green algae, are ubiquitous in most water bodies worldwide and can produce harmful byproducts called cyanotoxins. In 2022, the Centers for Disease Control and Prevention recorded 372 harmful algal bloom (HAB) events nationally, resulting in 95 human illnesses and more than 100,000 cases of illness in animals. Just last fall, two dogs died near Vancouver after consuming a previously undiscovered form of cyanobacteria in the Columbia: benthic mats that stick to riverbeds, as opposed to planktonic cyanobacteria, which floats freely in water columns.
“Cyanobacteria have been around for about three billion years, and so they’re very good at adapting,” said Wayne Carmichael, a former professor at Ohio’s Wright State University. “Given all they need, which is nutrients, light and proper temperatures, they’re going to be major contributors and competitors in all systems.”
Carmichael, now retired and living along Oregon’s coast, helped pioneer the identification of specific cyanotoxins back in the 1970s and 80s. There are three main groups — hepatotoxins, neurotoxins and dermatotoxins — each of which have several chemical variants with wide-ranging impacts on human and animal health, including death in extreme cases, but also respiratory distress and convulsions, failure of the liver and lungs, skin rashes and more.
“Pretty much any cyanobacteria is capable of it. They have the genetic material, it’s just whether it’s expressed or not,” said Carmichael. “Expression of the toxin really has to do with the biomass, and the biomass is influenced by nutrient enrichment and pollution.”
HAB events are growing both in terms of frequency and magnitude, according to the U.S. Environmental Protection Agency, and that’s primarily because nitrogen and phosphorus are overly abundant in the environment. Whether it’s from fertilizer runoff, discharge from a sewage treatment plant or even airborne pollution from exhaust pipes, these nutrients fuel rapid cyanobacteria growth, resulting in eutrophication that starves aquatic animals of oxygen and creates more opportunities for cyanotoxin production.
Climate change is another important factor. Cyanobacteria thrive in water heated by global warming, and more extreme precipitation only hastens the leaching of nutrients into waterways. Cyanobacteria also prefer a stagnant habitat, Carmichael said, and the Columbia’s 14 mainstem dams restrict free flow, making the river more akin to a series of reservoirs.
Seeing green
In recent years, HAB events in the Columbia River have primarily occurred near Vancouver, the Portland area and Tri-Cities. Patches of green dot the river’s surface from Skamania County to Wasco, though, and while each individual case varies, there is another organism affecting local waters. One that’s less of a threat to health, and more so a nuisance: milfoil.
Eurasian watermilfoil is an invasive, feathery plant that returns perennially and grows with great density. Although connected to the riverbed, parts of milfoil patches often break off, which enables the plant to easily travel downriver and establish roots elsewhere. Already, it’s causing problems for wing foilers, kite surfers and other folks harnessing those famed Gorge winds.
“If someone’s coming in, we’ll always ask them, ‘How are the weeds today?’ said longtime windsport enthusiast Cimeron Morrissey. “When you hit a weed ball and you’re going very fast, you stop dead and get catapulted — that’s no fun.”
Back in the 1980s, when Underwood resident Mark Prussing started actively recreating in the Mid-Columbia region, he said that milfoil didn’t exist in the river. Now, it’s overtaking popular launch spots for wind sports, including Doug’s Beach near Lyle, “The Hatch” off Spring Creek Hatchery Road and Bob’s Beach in Stevenson. There’s also a large clump near The Hook in Hood River, lining the shore of Wells Island.
“That’s now growing east,” said Prussing. “Eventually, I think it’s going to make access from the waterfront park really difficult,” adding that he’s heard of someone breaking their foot after colliding with milfoil earlier this summer.
Morrissey explained how, even if she doesn’t get thrown off, she has to stop, flip her board over and manually remove all the stems if enough milfoil accumulates. Now, she said that winging sometimes just feels like a game of avoiding and evading, and both agreed the problem is only becoming more pronounced.
“It’s just getting worse all over. It seems like the difference from last year to this year is quite visible,” said Morrissey.
Mitigation and what to look out for
As an invasive plant, milfoil is difficult to get rid of. Since Daryl Stafford joined the Port of Hood River as the waterfront and recreation manager in 2018, it has hired licensed professionals to chemically treat milfoil and seaweed in the marina twice every summer using systemic herbicides approved by the U.S. Army Corps of Engineers (USACE). This year, the contractors from AquaTechnex are coming three times because the growth is so thick, costing the port about $12,000 in total.
Stafford emphasized monetary constraints for treating other locations and said its primary responsibility is maintaining access to the river along port-owned property. According to her, open water removal requires different, more expensive solutions, such as large machinery and diving teams to physically weed the plants.
“That would be really hard with the limited resources we have, and again, you can’t just send anybody out there. It takes a certified diver and a support team for that, boats and places to haul it,” said Stafford. “If milfoil started affecting the on-land beach launch sites, we would definitely be organizing cleanups and things that our staff and volunteers could manage.”
Plus, the jurisdictional question is fuzzy. Wells Island, for instance, is federally owned by the U.S. Forest Service, and USACE oversees water management on the Columbia, so the port doesn’t have authority to mitigate milfoil in open water.
USACE was not able to provide comments to Columbia Gorge News by press deadline.
Having observed hundreds of treatments nationally and internationally, Carmichael cautioned municipalities against physical and chemical removal, both of which offer immediate results but require repeated treatment. To fully eradicate milfoil in the long term, a habitat needs aerobic, or oxygenated, conditions that encourage the growth of native microbiota, fungi and bacteria. These organisms, in turn, decompose nutrient-laden sediments that drive milfoil growth, just like cyanobacteria.
“Essentially, you recreate the food chain, a natural food web that didn’t exist because you’ve created a situation where only the cyanobacteria can proliferate,” said Carmichael. “It’s not necessarily more expensive, but you don’t get your immediate response so people can swim the next day.”
In terms of monitoring HAB events, Carmichael said that Oregon has been more proactive compared to most of the country. The Department of Environmental Quality actively measures cyanobacteria levels in 49 lakes and reservoirs across the state, and Oregon’s Health Authority issues warnings as needed. But the agencies don’t keep tabs on every body of water, including the Columbia.
From Memorial Day to Labor Day, Columbia Riverkeeper, an environmental nonprofit with offices in Hood River and Portland, regularly tests for E. coli, a bacterium found in fecal matter, and conducts visual HAB assessments along beaches in the Gorge, absent a state-level effort. Lorri Epstein, the organization’s education and science director, has one key piece of advice: “When in doubt, stay out.”
Since smaller bodies are more susceptible to the negative impacts of HABs, people with children or pets should remain especially wary of choosing a local place to swim or recreate, and avoid ingesting river water at all costs. While it’s impossible to tell if cyanotoxins are present just by looking at a potential algal bloom, Epstein explained several indicators to keep in mind.
“Cyanobacteria looks like paint slick. If you dip a piece of wood in it, the wood would be coated. It’s not filamentous, so it doesn’t hang down,” said Epstein. “Cyanobacteria isn’t always blue or green, so even scummy or scuzzy-looking water can be a sign as well.”
While less common, cyanobacteria can appear as white, red, brown and black, and can take the form of mats stuck to the riverbed. Before choosing which beach to spend your afternoon, Epstein suggested that folks consult Swim Guide, an app that uses E. coli data from Columbia Riverkeeper and other organizations to determine whether shorelines, in Oregon, Washington and around the world, are safe for swimming.
“Our goal is not to scare people away from the Columbia ... We want to arm people with information and put them in a situation where they can enjoy the Columbia with confidence,” said Epstein. “You just have to operate out of an abundance of caution.”
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