EMERGENCY ALERT! Residents of Salem, Oregon, and several surrounding communities received this message on their cell phones on May 29. A toxic algal bloom in Detroit Lake contaminated the communities' water supply and "sensitive" residents were warned not to drink their tap water until further testing is done. Those sensitive populations include children under six, pregnant or nursing moms, dialysis patients, and anyone who is in poor health, or who has a pre-existing liver condition or compromised immune system…oh, and pets. As if that weren't enough, the warning also said not to cook with the water, so that pretty much affects everyone, sensitive or not. A "boil water" advisory was not part of this warning, however, because boiling won't kill the cyanotoxins and can even increase the level of toxicity. Most home filtering or purifying devices won't help either.
Cyanotoxins are produced by blue-green algae (aka "cyanobacteria"), which occurs naturally in lakes and other surface waters. But in warm water containing a lot of nutrients, the algal blooms can become toxic. Officials aren't sure why the harmful blooms are occurring right now in Detroit Lake, but it could be that "the rivers are bringing a lot of nutrients into the lake at once" as the reservoir is filled to its "full pool" level for the summer.
Results from further testing will be available today. In the meantime, nearly 200,000 people are making do. Bottled water supplies were quickly depleted at area retailers as residents scrambled to find water for drinking and cooking.
Normally, tap water in the United States is safe and healthy. But this week's incident reminds us how vulnerable our drinking water is to disruptions when something goes wrong—natural or otherwise.