— City of Salem (@cityofsalem) July 3, 2018
The scummy, green colored “algae” blooms caused by Cyanobacteria that have plagued Florida’s lakes and riverways this summer have also been causing trouble in the fresh waters of the West Coast.
Oregon officials are already used to issuing the recreational advisories that come with the increasingly frequent summer blooms on Detroit Lake reservoir southeast of Salem, but they were caught by surprise in early June when it was found that cyanotoxins, toxins produced by certain species of cyanobacteria, were present in the City of Salem’s water supply, which serves nearly 20,000 residents.
The cyanotoxin microcystin, when ingested, can cause abdominal pain, vomiting, diarrhea, kidney damage, and acute liver failure. There is some evidence that long-term exposure to low doses of cyanotoxins may be linked to cell proliferation in cancers. Although the concentration of toxin in the Salem water supply was safe for most people to use and drink, a “do not drink” advisory was sent out for children under six, pregnant women, the elderly, and those with vulnerable medical conditions. The advisory stayed in place through the month of June as a precaution until a treatment process could be implemented at the water treatment plant, although toxin levels have not been above EPA guidelines since June 18.
The advisory was lifted on July 3.
“The health and safety of our residents and drinking water customers remains our highest concern,” said Salem City Manager Steve Powers said in a press release.
Treatment processes for cyanotoxins can vary depending on whether the cyanotoxins remain in the bacterial cells or have been released into the water. Some treatments, such as oxidation, may cause intact cells to lyse, potentially making the problem worse by releasing more toxins. Boiling water can kill the bacteria and other microbes in tap water, but will not reduce the toxin. Boiling the water may only make it worse, as the volume of water is reduced and the concentration of toxin becomes higher.
The vast majority of water treatment plants are woefully equipped to deal with algal bloom toxins, even though the EPA estimates that 30-48 million people depend on lakes and reservoirs that may be periodically contaminated by algae toxins.
The situation in Salem is reminiscent of the 2014 water crisis in Toledo, Ohio, when cyanobacteria bloom formed over the city’s water intake in Lake Erie and toxins were found contaminating the city’s water supply. At that time, 500,000 residents were advised to stop using tap water. Unlike in Salem, this ban was for all ages, forcing residents to use bottled water for days until the situation abated from a combination of wind moving the bloom away and use of activated carbon to remove and absorb the toxins.
As algae blooms are forecasted to become more frequent and more severe due to warming temperatures and runaway nutrient pollution, it is clear that something needs to be done to address current and future contaminations of the water systems. Cities in Oregon are already investing in sophisticated new water treatment plants. Jonathan Modie, a communications officer from the Oregon Health Authority told Newsweek, “This was a real wake-up call for us.”
Source and Further Readings
Control and Treatment – EPA
Tap Water Ban for Toledo Residents – New York Times
As Salem Frets About Toxic Algae, Should the Rest of Oregon? – Oregon Public Broadcasting