Posts
Large
Algae Bloom Still Ongoing As Toledo Officials Declare Water Safe
to Drink
14
February, 2014
(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.
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