Last weekend, the City of Toledo advised its customers against drinking the city’s tap water. The municipal ban left 500,000 Toledo and Michigan residents without drinking water for three days, which was contaminated by a toxin produced by an algae bloom in Lake Erie.
Cyanobacteria, commonly referred to as blue-green algae, are a serious problem in surface water sources in the United States. In drinking water, they are most commonly known for causing taste and odor problems. In some cases they can also release cyanotoxins, which raise health concerns related to the liver, nervous system and gastrointestinal system.
In Toledo, a cyanobacteria bloom is an annual occurrence and was recently quite visible near Toledo’s water intake system on Lake Erie. Tests last week from the city’s water treatment plant confirmed the detection of microcystin — a cyanotoxin produced by the harmful blue-green algae. City officials were told by the Ohio Environmental Protection Agency to issue a “do not drink” order for its entire population.
The cause of the annual cyanobacteria bloom in Toledo is primarily phosphorus from farm fertilizer runoff, and the amount of phosphorus determines the bloom’s size. Scientists are also learning that another farm fertilizer, nitrogen, affects the size and composition of the annual bloom.
The “do not drink” incident in Toledo is a reminder that the protection of our source waters is critical to the protection of public health.
Much like Toledo, cyanobacteria is prevalent in Iowa. At Des Moines Water Works, phytoplankton studies are performed on Des Moines’ sources waters – the Raccoon and Des Moines Rivers. Cyanobacterial and algal counts comprise the phytoplankton studies. These studies determine the numbers and species of the most common phytoplankton viewed microscopically.
Both cyanobacteria and algae grow in response to warm weather and nutrients (i.e. nitrogen and phosphorus), and can proliferate in the source water to a degree that affects water treatment operations.
Des Moines Water Works staff treats for unfavorable tastes, odors, and toxins by dispersing powdered activated carbon throughout the water (much like when water is ran through a carbon filter). Chlorination of the water also helps remove or destroy bad tastes, odors, and cyanotoxins.
When the phytoplankton counts become high, Des Moines Water Works staff can respond by switching from one river to the other, by maximizing use of the infiltration gallery system (a series of underground pipes located throughout Water Works Park next to the Raccoon River), and by using water stored in aquifer storage reservoirs or water produced at the L. D. McMullen and Saylorville Water Treatment Plants.
Currently there is not a federal standard for blue-green algae or their toxins in drinking water; however, a growing number of states are introducing their own guidelines and the U.S. Environmental Protection Agency has named cyanotoxins as a candidate for federal regulation.
Strategic water treatment, testing, and federal regulation of cyanotoxins are worthy, but a remedy at the source of the contaminant is more urgent. The only viable option to curtail the presence of algae that can potentially cause toxins to infiltrate our drinking water is changing upstream land practices.
Creating buffers, like plants and trees that stand between farms and the water, may help catch fertilizer chemicals before they get into water ways, spurring algae growth. Farmers could also, theoretically, use less fertilizer, though there are no regulations in place as of now.
Farm runoff is not very regulated, so the drinking water contamination incidence in Toledo could happen again, and here in Iowa.
This should be a call to action for citizens to advocate for cleaner source water and to question if voluntary water protection measures work.
Top photo credit: A glass of algae filled Lake Erie water, near the Toledo water intake crib, on Sunday via The Toledo Blade.