Algae-produced microcystin levels in Lake Erie — the toxin that fouled municipal water for three days in 2014 — have remained low near Toledo’s drinking water intake crib, according to a review of daily tests performed by city chemists since late June.
Andy McClure, Toledo water-treatment plant administrator, said tests revealed the algal toxin is present in the water near the city intake crib, but only at low levels.
“We have been in the single-digits, [parts per billion] once or twice this summer,” Mr. McClure said. “Between lower nutrient loads and weather patterns, it has not been a very productive year for algae.”
The City of Toledo water intake crib is surrounded by algae in Lake Erie in 2014.
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The city began testing for microcystin in 2011, and the initial sample tested on Sept. 12, 2011, showed lake water levels at the intake mechanism greater than 5.5 parts per billion. The exact level that day was unknown since the sample was not diluted and tested for a precise number.
The level in the raw water is irrelevant for consumers, Mr. McClure said, as long as the treatment process removes enough of the toxin to take it below acceptable levels by the time it leaves the Toledo drinking water treatment plant.
Toledo’s treated tap water microcystin toxin level was greater than 3 parts per billion when the August, 2014 crisis began, records show. That level was three times the World Health Organization’s cutoff of 1 part per billion for safe drinking water.
There has been no detection in the tap water this year, Mr. McClure said.
Tests showed the level from the raw lake water was 0.6 parts per billion on June 29; it was up again to about 0.7 parts per billion in a July 17 test; it spiked on July 20 to 1.6 parts per billion, and fell the next day to below 0.2 parts per billion.
It jumped again on July 31 to just over 1 part per billion in the raw water taken via a pipeline that runs from the intake crib, which is three miles from shore, to the city’s low service pump station. More recently, the raw water microcystin level was 1.8 parts per billion on Aug. 12.
Mr. McClure said the city tests for microcystin daily even though the Ohio Environmental Protection Agency only requires weekly testing.
Samples are acquired via that pipeline, which runs parallel to the drinking water pipe. City employees travel by boat to the intake weekly and take samples inside and around the 1941 structure.
Western Lake Erie has had a chronic algae problem nearly annually since 1995.
The National Oceanic and Atmospheric Administration predicted in the spring that this year’s algae bloom would be milder than last summer and most likely about average in size.
Rick Stumpf, a NOAA oceanographer, said that prediction is so far accurate.
“This year, the bloom we are looking at is smaller than the last couple of years and has been running well below that of the last several years starting from mid-July to the present,” he said. “There is a little bit of an increase in Maumee Bay this week — the toxin is a little bit up — but nothing drastic.”
Mr. Stumpf said the current concentration of microcystin in Western Lake Erie easily can be neutralized.
Levels spiked to 33.1 parts per billion on July 11, 2012, for surface water near the intake, tap water levels were just 0.1 parts per billion that day. Two days later, the surface level was 12.14 parts per billion.
“If they know there is a bloom, they can be even more effective with the treatment,” he said. “The toxins we have seen so far are at concentrations the city had easily removed in the past.”
The toxin is absorbed by powdered activated carbon, which is later removed. Aluminum sulfate is added to the process, which helps clump together algae and other particles in water, facilitating removal by settling or filtration. Chlorine then breaks down the microcystin to a level not harmful to the public, Mr. McClure said.
The U.S. EPA in May, 2015, changed the threshold and announced that those school-age and older can drink tap water with up to 1.6 parts per billion of microcystin in it. Anything more is unsafe, the agency said. That amount is much more flexible than the World Health Organization’s 1 parts per billion guideline that Ohio had used previously.
A new limit of 0.3 parts per billion was set last year for infants, children younger than 6, pregnant women, nursing mothers, people with liver conditions, and those on dialysis.
Experts familiar with Western Lake Erie said water treated at Toledo’s Collins Park Water Treatment Plant is safe to consume.
“We’re not seeing any anomalies this year,” Chris Winslow, interim Ohio Sea Grant and Ohio State University Stone Laboratory director, said. “This year is producing the toxins we’d expect for these conditions.”
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