Like high nitrate concentration in the Des Moines and Raccoon Rivers, another agrotoxin from excess nutrients from intensive agricultural production upstream is threatening central Iowa drinking water sources.
Cyanobacteria, commonly referred to as blue-green algae, grow and multiply quickly where there are high nutrients (nitrogen and phosphorus). Certain forms of blue-green algae can also produce toxins that can make humans and animals sick. When cyanobacteria counts rise, there is greater potential for the presence of cyanotoxins, which raise health concerns related to the liver, nervous system and gastrointestinal system.
Microcystin is the cyanotoxin found in the finished drinking water of Toledo, Ohio, in 2014, that prompted the city to issue a “Do Not Drink” order for its 500,000 customers. The cyanotoxin was released by a cyanobacteria bloom in Lake Erie at the time, near the city’s water intake system.
Much like Toledo, Des Moines Water Works uses surface water to produce drinking water for 500,000 central Iowa customers.
Des Moines Water Works recently began a more aggressive testing regimen for the presence of harmful cyanotoxins when elevated cyanobacteria levels are present in raw water sources. While many water utilities do not have equipment to test for these toxins, Des Moines Water Works recently invested in instrumentation that allows staff to monitor for microcystin and cylindrospermospin, per U.S. Environmental Protection Agency recommendations, as well as two additional known cyanotoxins – anatoxin and saxitoxin. Des Moines Water Works now routinely samples three times per week during the warmer months of the year, and more frequently when necessary.
Des Moines Water Works’ treatment process has limited ability to thoroughly remove these toxins from finished water; however, the ability to avoid the river source with the greatest amount of toxins remains the single most effective strategy to protect customers. Des Moines Water Works must remain nimble to the emerging science and public health considerations of these toxins. Staff from Des Moines Water Works is working with state regulators from Iowa Department of Natural Resources and public health and emergency management personnel, to communicate health advisories if microcystin or cylindrospermospin are detected in the finished drinking water, as prescribed by EPA.
Des Moines Water Works is committed to delivering safe, affordable and abundant drinking water to its customers. Finished drinking water continues to meet or exceed drinking water quality standards; however, it is increasingly challenging. Des Moines Water Works remains advocates for a holistic approach for addressing water quality in Iowa, including promoting precision conservation practices to reduce excess nutrients, E. Coli, eroded soil, and emerging contaminants – much of which can be attributable to agricultural production.