An algal bloom in Oregon’s Willamette River prompted a health advisory from the Oregon Health Authority Tuesday, with the agency warning Oregon residents not to touch, drink or inhale droplets from the river.
The Oregon Department of Environmental Quality has taken samples of the bloom and is waiting to get back test results, which will determine the species of algae and the amount of algal cells in the bloom. Rebecca Hillwig, Environmental Health Specialist at the state DEQ, told ThinkProgress that the OHA will determine whether or not to lift the health advisory based on these results, since the determining the species of the algae will also determine the toxicity.
In the meantime, however, the OHA is warning people and pets to stay away from the river, especially the part where the algae’s been spotted — an area that extends “at least a couple thousand feet of river bank along the channel,” Larry Caton, who collected samples for OHA Tuesday evening, told KOIN 6.
Hillwig said this is the first time that she knows of that a blue-green algae bloom has been identified in the Willamette River. Typically, she said, blooms in Oregon occur in lakes and ponds — not major rivers. But she thinks Oregon’s unusually hot, dry summer made conditions in the river more conducive to algal blooms by driving the water flow and levels in parts of the river down and the temperature up. That, along with phosphorus and nitrogen pollution entering the river, helped cause the algal bloom.
“It’s kind of that perfect storm where all those environmental triggers are in place and a bloom develops,” she said.
Most of Oregon is currently experiencing moderate to extreme drought conditions. Oregon’s also experienced more frequent hot days in recent years — over the last 10 years, Oregon has had its last 90-degree day of the summer on or after September 10. This is three days later than the state’s average end point for 90-degree days — September 7. The prospect of the longer, hotter summers that could hit Oregon as the climate changes has Hillwig worried that the state could see more incidences of algal blooms.
Hans Paerl, Kenan Professor of Marine and Environmental Sciences at the University of North Carolina Chapel Hill, told ThinkProgress that these fears aren’t unfounded. Paerlexplained in a letter in Science Magazine in 2008 that cyanobacteria — also known as blue-green algae — grows better in warmer temperatures than organisms like diatoms and green algae. Paerl told ThinkProgress that warmer temperatures and decreased ice cover have caused bigger blooms in some regions and have also caused regions that don’t typically experience blooms to start seeing them.
“So it’s bad enough that we have too many systems that we have too high a nutrient load in them — or too much nutrients coming in — that’s causing the blooms, but secondly, climatic change — particularly warming — can lead to exacerbation of those blooms,” Paerl said.
Rising temperatures could mean that officials need to further lower nutrient loading limits for waterways in order to compensate for the growth boost the algae gets from the heat. And heat, Paerl said, isn’t the only climatic effect that could impact algal bloom growth. Extreme rainfall — which is predicted to become more common in many parts of the world as the planet warms — can wash large amounts of bloom-enhancing phosphorus and nitrogen into a water system, creating ideal conditions for an algal bloom. If a period of extreme rainfall is followed by drought or high temperatures, that exacerbates the bloom conditions even further.
“Say you have a very wet spring with lots of rainfall coming in and then you have an extremely dry summer, then you pretty much have the perfect conditions for these blooms to really go to town, so to speak,” Paerl said.
Toxic forms of blue-green algal blooms can disrupt ecosystems, inhibiting the growth of — or even killing — fish and plankton and leading to death and neurological and liver problems in mammals such as cattle and dogs, Paerl said. They can also cause major disruptions in water supplies, as a toxic algal bloom in Lake Erie, which temporarily poisoned the water supply for about 400,000 people in Toledo, Ohio, did last month. If humans ingest or breathe in particles of blue-green algae, they can suffer “numbness, tingling and dizziness that can lead to difficulty breathing or heart problems, and require immediate medical attention,” according to the OHA.
Hillwig said the algal bloom won’t impact any commercial water supplies. But the agency is concerned about encampments of homeless people along the river, who might drink directly from the river or try to boil or filter the water before drinking it — methods that won’t work in removing the algae’s toxicity, if it is in fact found to be toxic. Hillwig said people who were taking samples for the OHA talked to homeless people along the river, and that the agency has put up warning signs near the access areas of the river.
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