(Large algae bloom still visible in Lake Erie satellite shot on August 4, 2014. Image source: LANCE-MODIS.)
Warming, more toxic waters. It’s a problem directly driven by human-caused climate change. And for Toledo, Ohio, this weekend, it’s a reality that was starkly driven home as water services to half a million residents were suddenly shut off. There, in the waters of Lake Erie, a massive bloom of freshwater cyanobacteria pumped out enough poison to put human health at risk and force Ohio officials to declare a state of emergency.
Emerging Threat to Public Health
In Northern Ohio, water safety officials have been nervously testing Lake Erie supplies for many years now. Microbial blooms in western Lake Eerie were on the rise and the worry was that the new blooms may pose a future health threat as both climate change and agricultural run-off intensified.
By 2011, the wettest summer on record and warm waters in Lake Erie helped trigger a major outbreak of cyanobacteria blooms which ultimately resulted in more than 10 billion dollars in damage due to fouled waters, toxic beaches, and losses to the fishing and tourism industries of Lake Erie’s bordering states. Last year, a massive bloom caused some small northern Ohio towns to temporarily cut off water supplies. By last weekend, the entire water supply of Toledo, Ohio was under threat from the microbe-produced toxin called microcystin.
Water Poisoning by Microbes
Microcystin is a potent toxin produced by the small-celled, fresh water cyanobacteria. The substance is unsafe at levels greater than 1 part per billion in drinking water (according to the World Health Organization). Consumption of the toxin results in headaches, nausea and vomiting. Microcystin is directly toxic to the liver with exposure resulting in severe damage. It also results in damage to the digestive system and low levels of exposure have been linked in studies to various forms of abdominal cancer.
Since the toxin is a chemical that has already been produced by bacteria, usual sanitation methods, such as boiling water, are ineffective and may even help to concentrate the poison, making it more potent. So the toxin must be prevented from entering the water supply at the source — which can be difficult if much of the water source is contaminated, as is the case with Lake Erie.
A Threat Driven By Climate Change and Human Activity
As waters warm, they host larger and larger blooms of cyanobacteria harmful to animal life, including humans. The microbes thrive in warm, nutrient-rich water. And under climate change waters both warm even as runoff in certain regions increases due to more frequent bursts of heavy rainfall. This has especially been the case for the central and north central sections of the US, this year, which have suffered extensive and frequent downpours together with record hourly and daily rainfall totals in many areas.
The deluges flush nutrients down streams and into major bodies of water. The water, warmed by human-caused climate change, are already a haven for the cyanobacteria. So the blooms come to dominate surface waters. In addition, the runoff contains added nutrients due to large amounts of phosphorus and other agriculture-based fertilizers. It’s a combination that really gives these dangerous microbes a boost. Under such conditions, the massive resulting blooms can turn the surface lake water into green sludge.
Dead Zones, Anoxic Waters
(Green cyanobacteria in Lake Erie during the large algae bloom of 2013. Image source: University of Michigan.)
Eventually, the cyanobacteria leech the surface waters of nutrients and begin to die out. As they do, they undergo decay which strips oxygen from the waters. Through this process, dangerous, anoxic dead zones radiate from areas previously dominated by large cyanobacteria blooms. The dead zone and toxin producing bacteria often result in large-scale fish kills and the wide-scale fouling of waters that can be so damaging to various industries. However, the dead zones themselves are havens for other toxic microbes — the hydrogen sulfide producing kind.
Water is Declared Safe — Information Still Unavailable to the Public
Today, water safety officials lifted the ban on water use for Toledo, claiming that water was now safe to use and drink after the water system was properly flushed. Officials apparently conducted six tests to confirm water supply safety but have not yet made results public. Personnel with the EPA unofficially stated that microcystin levels were at 3 parts per billion on the day the water was declared unsafe but that water was now safe for residents.
The declaration was met with widespread criticism due to the fact that data on water testing was not made publicly available, reducing confidence in the safety officials’ assertions and causing many residents to question their veracity. State and city water officials say they plan to post the data on their website, but have yet to confirm a time.
Meanwhile, the large cyanobacteria bloom is still ongoing. Experts expect the bloom to peak sometime in mid September and then begin to recede with the advent of fall and cooler weather. With more than a month and a half still to go, Lake Erie water troubles may just be starting to ramp up.