Every summer, a handful of Oregon’s most popular crystal blue lakes are shut down by public health authorities because of harmful algae blooms. Sometimes called blue-green algae, the blooms are caused by a toxin-producing bacteria, often forming a green paint-like scum on the surface of the water that can cause health problems for humans and can kill livestock and pets.
While most blooms are only a minor inconvenience, state and federal health and environmental authorities are concerned that climate change and runoff from agriculture and lawn fertilizer are driving an increase in the frequency and severity of harmful algae blooms, putting people, pets and livestock at greater risk.
Yet a lack of funding in Oregon and most other states has led to a haphazard system of surveillance and testing of reservoirs and lakes used for drinking water or outdoor recreation, leaving countless bodies of water unmonitored for these harmful blooms.
“The actual acute risk to humans is minimal, but unless we address water quality conditions in their totality, the blooms will get worse,” said Dr. Wayne Carmichael, one of the world’s leading experts in harmful algae blooms who has now retired to the Oregon coast. “We’ll have more of them producing toxins, more frequently and in longer durations. And sooner or later people will become more acutely poisoned.”
Cyanobacteria are among the oldest life forms on Earth. Scientists credit them with producing much of the oxygen that allowed other forms of life to develop billions of years ago.
“They’re not really algae, they’re this little single cell organism that goes through photosynthesis just like algae, and they use the same food source, phosphorus and nitrogen,” said Rebecca Hillwig, an environmental health specialist who runs the state’s Harmful Algae Bloom Surveillance Program for the Oregon Health Authority. “They’re actually good bacteria. They just get a little bit out of hand.”
Under the right conditions, the bacteria can multiply rapidly creating huge colonies of bacteria that become visible blooms in the water. Some of the blooms are harmless, while others will produce toxins, and there is no way to tell just from looking.
The toxins can cause eye and skin irritations for those swimming or boating in the water. Ingesting the toxin can lead to more severe symptoms, including cramping, vomiting and diarrhea.
While exceedingly rare, there have been documented cases of hospitalizations and fatalities linked to recreational exposure to HABs. One investigation by the Centers for Disease Control and Prevention found that in 2009 and 2010, three states reported 11 outbreaks of individuals exposed to blooms in recreational settings, and between 2007 and 2011, at least 273 people became sick after eating food contaminated with these toxins.
“The public is at risk, but it’s a small risk,” Carmichael said. “You’d really have to get in there and make serious contact with the water to get an acute poisoning.”
With few practical ways to counter the blooms, public health authorities have focused on keeping people out of affected waters. Since 2006, OHA has issued 12 advisories warning people to stay out of five Central Oregon lakes, lasting anywhere from a few days to several months. Statewide, the number of advisories issued per year is going down, but Hillwig said the numbers don’t tell the entire story.
Two years ago, a 10-year grant from the CDC providing money for monitoring blooms in Oregon ended, leaving a less robust, voluntary surveillance system in place.
The state relies on a patchwork of public agencies, such as parks departments, city governments or the U.S. Forest Service, to monitor water bodies in their jurisdictions for blooms, test for toxins and inform state officials if the levels exceed safe limits. OHA will then issue an advisory warning people to stay out of the lakes until the bloom resolves.
“Because of the limited resources, they do a lot of triaging,” Hillwig said. “The forest service has many, many lakes across Oregon, so they just can’t monitor all of them.”
Staff with the Deschutes National Forest check only a handful of lakes on a regular basis, targeting their efforts to the most-highly trafficked lakes where a harmful bloom would have the greatest impact. Those include Wickiup and Crane Prairie Reservoirs, Lake Billy Chinook, as well as Lava, Paulina, Odell and Suttle lakes.
Hillwig said the agency is getting more reports of blooms than ever before. But not every bloom can be tested, and many don’t result in advisories. This year, OHA plans to list on its website not only those lakes with active advisories, but those with identified blooms even if toxins don’t exceed the safe threshold.
“So people aren’t getting the impression that if there’s not an advisory in place, then it’s ok,” Hillwig said. “We’re trying to get the word out that they are potentially everywhere and just to be forewarned to be on the watch.”
Although historical bloom data is lacking, scientists believe that warmer temperatures are allowing the bacteria to thrive and crowd out other types of algae. That has extended the geographical spread of the bloom into more northern latitudes, and increased the size and frequency of those events.
“There are indications that our season is getting longer,” Hillwig said. “We can now see them from the beginning of May into January, and the blooms appear in some cases to be getting larger.”
CDC officials said that mirrors trends in harmful algae blooms nationwide, as climate change has led to higher temperatures and more extreme weather. More intense rainfall drives nitrogen and phosphorus from urban and agricultural sites into lakes and reservoirs. One study found that the Pacific Northwest, for example, had a 12 percent increase in the heaviest precipitation events from 1958 to 2012. Droughts in the Southwest, meanwhile, have killed off other types of algae, leaving more nutrients for cyanobacteria.
“The frequency is increasing,” Carmichael said. “We’ve just created conditions that they like to grow in, complicated perhaps by global warming.”
Part of that stems from the development of water bodies. Damming rivers to create reservoirs creates standing water fed by rivers and stream that load the lakes with the nutrients and allow the bacteria to thrive. Stocking lakes with fish can alter the ecosystems, allowing bacteria to crowd out other algae.
“Human activities allow them to reach much denser proportions, and they last longer before they run out of nutrients,” said Tim Otten, a former Oregon State University researcher and founder of Bend Genetics, a water quality monitoring and consulting firm.
Those nutrients are mainly the nitrogen and phosphorus from fertilizers used for agricultural and residential lawns. Concerns are heightened when blooms appear in lakes or reservoirs used for drinking water.
“There’s very little regulatory oversight and it remains unclear what level of monitoring is being voluntarily conducted by drinking water utilities,” Otten said.
In 2014, a massive algae bloom in Lake Erie forced some 500,000 residents of Toledo, Ohio, to use bottled water for drinking, washing dishes and bathing their children. The toxins cannot be cleared by boiling or chlorinating water or with personal filtration devices. Utilities must turn to carbon filters to remove it safely.
“Toledo was definitely a watershed event,” said Jay Martin, an associate professor of food, agricultural and biological engineering at Ohio State University. “It really got a lot of focus on harmful algae blooms.”
The Toledo fiasco led to an agreement signed earlier this year by Ohio, Indiana and Ontario, Canada, to reduce the amount of phosphorus flowing into Lake Erie by 40 percent. A joint Ohio State-University of Michigan study identified a number of strategies to achieve that reduction, mainly focusing on limiting the use of fertilizer in agriculture. That could include subsurface application of fertilizer, rather than the common practice of scattering pellets of fertilizer on top. That would not only reduce the amount of fertilizer needed, but limit the amount that can be washed by rain into the rivers and streams that feed Lake Erie.
Other strategies include planting cover crops that will hold nutrients in the soil during the winter and spring, or using wetlands and buffer strips of land to keep phosphorus out of rivers and streams.
Martin said many of the farmers in key areas of the watershed feeding Lake Erie have already adopted some of those practices simply to be good stewards of the land or to cut their fertilizer costs. Others, he said, are waiting for the research to show that those steps will actually make a difference in reducing blooms and protecting the water supply.
Livestock, pets most at risk
Health officials have tried to track cases of human illness caused by harmful algae blooms, but believe it is likely vastly underreported. Minor symptoms are overlooked and gastrointestinal effects are often attributed to food poisoning or other similar causes.
Otten said, microgram for microgram, the toxin is more deadly than cobra venom or ricin.
“We’re not typically drinking surface water that’s untreated,” he said, “But pets and livestock will drink the water and keel over dead.”
Dogs and other animals are more likely to drink the water from lakes or lick their fur clean ingesting the toxin. Dogs are at risk at much lower toxin levels than humans. In Oregon and many other states, dog deaths, as well as livestock or wildlife kills, have served as sentinel events, alerting authorities that a lake may have exceeded safe thresholds.
Scientists are testing various strategies to counteract harmful algae blooms once they start, but it’s still an evolving science. Public health authorities are also shifting toward closing only affected parts of large lakes in order to minimize the economic impacts for lakeside resorts and vendors.
“We know it’s an economic burden,” Hillwig said, “But we want to mindful that it’s a protection of human health.”
Oregon has been ahead of most of states on monitoring blooms in part due to the CDC funding. Other states including California are only now trying to figure out how to deal with harmful algae blooms. Help may be coming from the federal government. Last year, the Environmental Protection Agency issued new guidelines for triggering alert postings and began monitoring blooms to determine the scope of the problem. The agency is also working on developing limits on toxins in drinking water.
Last week, the CDC launched a national database to track harmful algae blooms and their health impact, although for now the effort will rely on voluntary reporting from the states.
Meanwhile, researchers are trying to determine what the long-term risk of exposure to the toxins might be. The toxins are damaging to the liver and there is concern that repeated exposure through drinking water, even at low levels, could lead to liver cancer.
“We know this is a carcinogen, but we don’t know what the long-term effects are,” Otten said. “If there’s just a little bit of (toxin) in the water for 20 years, is that promoting liver cancer?”
Carmichael would like to see more attention in Oregon and nationwide to total watershed management, focusing on preventing the conditions that allow blooms to form. Spending that money upfront, he said, would be less costly in the long run than trying to clean up the water used for drinking or irrigation.
In the meantime, public health experts are trying to educate the public about the danger of harmful algae blooms to people and pets, advising them to stay out of waters with bloom even in the absence of the posted advisories.
“People need to be aware that just because a lake isn’t posted doesn’t mean that there couldn’t be something there that could harm you,” Otten said. “You have to be able to identify that this could be a potential hazard and not recreate in green scum.”
— Reporter: 541-633-2162, firstname.lastname@example.org