GIBRALTAR ISLAND, Ohio — This summer's western Lake Erie algal bloom — barring unusually strong northeasterly winds or unforeseen biological factors within the lake — should not keep Toledo and other shoreline communities from continuing to produce high-quality tap water, officials said Thursday.
Still, it’s expected to be the third or fourth largest on record since NASA began aerial surveillance in 2002, The National Oceanic Atmospheric Administration and other agencies announced during their annual briefing with reporters at Ohio State University’s Gibraltar Island.
Rick Stumpf, an oceanographer from NOAA's National Centers for Coastal Ocean Science in Maryland, coordinates the forecast, which also includes contributions from experts at Heidelberg University, Ohio Sea Grant, the University of Michigan, Ann Arbor-based LimnoTech, North Carolina State University, Stanford University, and the Washington-based Carnegie Institution of Science. The prediction is based on a composite of at least five scientific models, with the margin of error narrowing from year to year as more is learned about the relatively new realm of science.
NOAA and its collaborators agree the biomass of this summer's bloom will be about 7.5 on a scale of 10.
If the prediction holds, that would put 2017 behind the 2015 record algal bloom and the previous record set in 2011. It remains to be seen if there has been enough runoff for the 2017 bloom to surpass what western Lake Erie got in the summer of 2013, Mr. Stumpf said.
The prediction is for biomass only. Researchers are attempting to develop a model for predicting toxicity, but that is likely years away. They continue to stress the size of a bloom does not correlate to its toxicity.
The bloom behind the 2014 Toledo water crisis was average in size, but unusually toxic — partly because researchers now know there was a virus that caused algal cells to break open and release many more toxins in the raw lake water than what normally would be released for a bloom that size. Those findings were discussed in a recently published, peer-reviewed scientific paper, and were amplified by Mr. Stumpf at the briefing.
Though acknowledging insufficient science to predict toxicity, Mr. Stumpf said he believes Toledo is well-prepared this year. He described the city's 2014 algae crisis — when the algal toxin microcystin poisoned tap water distributed to 500,000 metro residents for three days — as a rare biological "perfect storm" that pushed toxins unusually deep and right over the city's water intake.
"I would have no hesitation about the water in Toledo at all this summer," Mr. Stumpf said, adding that the unexplained virus worsened the impact of sustained northeast winds.
By cracking open so many algal cells in the open lake water, the virus forced Toledo's Collins Park Water Treatment Plant "to chemically remove [microcystin], not just physically remove it," Mr. Stumpf said.
"It was not prepared to do that," he said.
Typically, a water-treatment plant doses incoming lake water with potassium permanganate and powdered activated carbon in its pre-treatment process to get particles of microcystis — the predominant type of algae carrying the toxin — to bind together and fall out. Then, it uses chlorine and other chemicals. With so many toxins released into the raw lake water, treatment would have been difficult for any plant caught in that situation, Mr. Stumpf said.
Mr. Stumpf said he has great confidence in advanced-warning systems deployed since then, especially buoys that monitor raw water quality and give water-treatment plant operators more time to prepare for an emergency.
One of the major developments since last summer is the deployment of a high-tech satellite called Sentinel-3a. Put into space by the European Space Agency several months ago, it gives NASA images of Lake Erie with incredible resolution - far sharper than the MODIS satellite NASA has had in outer space since the 1990s, Mr. Stumpf said.
“This certainly is not 1990s technology,” Mr. Stumpf said.
NASA is still using MODIS satellite images in conjunction with Sentinel-3a for the time being because the new satellite only makes passes above Lake Erie about every three days, he said.
NASA also makes regular passes over Lake Erie with low-flying aircraft. It is in the early stages of testing the applicability of drone technology.
This summer’s forecast was bumped upward slightly from July’s unusually heavy rain.
Laura Johnson, Heidelberg University National Center for Water Quality Research director, said northwest Ohio’s July rainfall is 400 percent higher than average this year, although she said that’s a bit misleading because July is usually dry in this part of the country.
“But July is pretty exceptional for us this year,” she said.
Her lab, based on samples collected at 18 monitoring stations since March, estimates western Lake Erie is being enriched by as many as 530 metric tons of total bioavailable phosphorus - more than twice the limit of 240 metric tons set as an annual goal by 2025 if area farmers can achieve a 40 percent reduction in runoff.
She and others said that although they need more cooperation from agriculture, this year’s heavy load is largely attributed to heavy rain. They said they remain confident practices to reduce runoff are working where they’re being used.
“It doesn't take a whole lot of storm flow to have the lake get a lot higher concentration,” Ms. Johnson said.
Microcystin is one of nature’s most potent toxins. It killed 75 people in a kidney dialysis center in Brazil in 1995. That resulted in a major U.S. Centers for Disease Control and Prevention investigation. That same year, a team of U.S.-Canada scientists found it becoming Lake Erie’s dominant algae, which it has been since.
“I cannot emphasize enough if there is a scum, stay out of the water,” Mr. Stumpf said. “Keep your pets out of it. Many people lose dogs every year to microcystis.”
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