OAK HARBOR, Ohio — The chief toxin produced by western Lake Erie’s 2013 algae bloom spiked at such extreme levels along the Ottawa County shoreline this week that it knocked the water-treatment plant serving 2,000 Carroll Township residents offline.
Poisonous microcystin, the toxin in Lake Erie’s most prevalent harmful blue-green algae, microcystis, was found at levels of 3.56 parts per billion in samples drawn from the Carroll Township facility, Heidi Griesmer, Ohio Environmental Protection Agency spokesman, said Friday.
That’s 3.5 times higher than the 1.0 parts per billion threshold for drinking water established by the World Health Organization.
The discovery was a fluke: The Ohio EPA does not require Ohio’s shoreline communities to test for microcystin, even though western Lake Erie has been coated by scum almost annually for weeks at a time since 1995.
Most area water-treatment plants test for microcystin voluntarily, though, Ms. Griesmer said.
In the case of Carroll Township, one of the region’s smaller treatment facilities, tests have been done only weekly.
“We don’t require them to sample at all,” Ms. Griesmer said. “We’re happy they’re sampling weekly.”
But Henry Biggart, Carroll Township water-plant superintendent, said he immediately sought approval from township trustees for more frequent testing.
He said he expects that to begin next summer.
“We’ve got to get through this first,” he said.
The Ohio EPA authorized Carroll Township to have a temporary, emergency connection to the Ottawa County Regional Water Plant, which serves Port Clinton, Oak Harbor, and other parts of Ottawa County.
That switch-over was not completed Friday night.
Carroll Township has 1,380 homes and businesses tapped into its water lines, serving roughly 2,000 people. Carroll Township residents were told to use tap water only for dishes and nondrinking uses until the advisory is lifted. No timetable was given.
At least 16 pallets of bottled water were distributed Friday to help residents get through what officials hope will be short-term emergency, Mr. Biggert said.
Microcystin is the same toxin that killed 75 people inside a kidney dialysis center in Brazil in the mid-1990s. An investigation by the U.S. Centers for Disease Control and Prevention showed the center’s water-treatment system had broken down, allowing the contaminated water inside the facility.
Water-treatment plants operated by larger cities, such as Toledo, have carbon-activated filtration, greater capacity, and other advantages that allow them to remove the toxin more easily.
But it’s expensive. Toledo has spent $3,000 to $4,000 a day just on that filtration, while sometimes spending more to knock out the toxin in other ways.
Carroll Township has a conventional ozone system that can be used effectively to combat the algae.
But the toxin that accumulated near the plant’s intake was at such levels that it overwhelmed the township’s facility, Mr. Biggert said.
“It’s at a concentration in the lake that’s so high we can’t treat it,” he said. “We’ve never had one like this before.”
Mr. Biggert said he made the decision to shut down the township’s water plant because he saw no other alternative.
Scientists are learning that the toxin and the algae act more independently of one another than previously thought.
For many types of algae, including microcystis, toxins are released as algae cells die. Yet, for reasons unknown, colorless and odorless toxins can remain in the water for weeks or months after algae blooms dissipate in the fall, said Linda Merchant-Masonbrink, Ohio EPA harmful algae bloom coordinator.
This summer’s forecast for algae by the National Oceanic and Atmospheric Administration called for a “significant” bloom. It typically peaks in mid to late-September, and fades by mid-October.
NOAA forecasters, though, said this summer's outbreak would likely fall short of the 2011 bloom, one of the worst ever.
Jeff Reutter, Ohio Sea Grant and Ohio State University Stone Laboratory director, said recently this year’s bloom is likely to be on the higher end of that NOAA forecast.
Even so, the dense concentration of toxins near Carroll Township’s intake illustrates how the size of an algae bloom isn’t necessarily synonymous with its toxicity, Mr. Biggert said.
“I’ve had algae conditions much worse than right now with lower toxin,” he said.
In Toledo, officials said Friday they had noticed an upswing in the toxin concentration at the Collins Park Water Treatment Plant, but said it was below the regulatory threshold.
Sampling showed levels of 0.42 parts per billion in Toledo, still less than half of the 1.00 parts per billion limit.
The Ohio EPA instructs municipal treatment operators to take extra precautions when levels exceed 0.25 parts per billion, Ms. Griesmer said.
Toledo officials said the city’s Department of Public Utilities has increased using permanganate, chlorine, alum, and carbon to fend off the toxin.