Jun. 10—Barring a dramatic change of events, western Lake Erie's algal bloom is likely to be smaller and milder in 2021 than it has been in recent years.
In their latest early season projection, issued Wednesday, the National Oceanic and Atmospheric Administration and Heidelberg University's National Center for Water Quality Research said sampling data through June 7 leads them to believe this summer's bloom severity — a simple index of 1 for lowest and 10 for highest — will be less than a 5.
The calculation is preliminary and will be firmed up when NOAA, Heidelberg, and others present their annual, official forecast for the summer on June 30.
The information sent out Wednesday was the latest in a series of early-season projections leading up to the main event. They began producing them after Toledo's 2014 water crisis, when area water-treatment plant operators, several businesses, and others wanted information about how the lake's conditions are shaping up even before the official forecast. The release issued Wednesday was the year's fifth.
It states, as have most others so far, that the bloom shouldn't be so bad because spring started out relatively dry.
And although the western Lake Erie watershed has at times been drenched by showers recently, they aren't making an appreciable difference yet.
Things could change, though, the scientists cautioned.
"Discharge of water from the Maumee River was below average in March and April, due to lower than average rainfall, which led to low phosphorus loads in early spring," the latest bulletin reads. "While weather systems in early June are bringing rain to the region, there is still uncertainty in the weather models on exact amounts, placement, and intensity of rainfall, which leads to uncertainty in the discharge and the phosphorous load. Later in June, we expect a return to normal rainfall with less uncertainty in the discharge."
Rick Stumpf, an oceanographer at NOAA's National Centers for Coastal Ocean Science in Silver Spring, Md., oversees the annual Lake Erie forecasts.
He said forecast models "have been successfully getting the rainfall this year going out several weeks," and adding that is why the forecast has not changed for several weeks.
"Our cautions involve the difficulty of getting that rainfall correct, particularly when there are strong gradients," Mr. Stumpf said. "At this point, I'm expecting conditions to hold."
Although weather patterns have at times been erratic and unpredictable — ask any farmer — this generally is not shaping up to be a wet year for the region.
Scientists have identified March 1 through July 31 as the most crucial time window for predicting blooms.
"This is a not a wet year, so July is highly unlikely to make a difference," Mr. Stumpf said. "We fully expect July to continue the pattern this year of slightly drier than usual, and July is normally a drier month than June."
Even though rainfall after March 1 seems to count the most, winters can affect runoff, too.
"Snowmelt can influence the March flow, and really pump up the nutrient load," Mr. Stumpf said. "This year, of course, had little snow to melt, and not much rain in March."
Laura Johnson, director of the Heidelberg research center, said this year's dry soil in early spring reminded her of the near-drought and drought conditions of 2016 and 2012, when algal blooms were smaller than the norm.
"Really what's important is how wet the soils are [when spring rains arrive]," she said. "It's going to take a lot to get the soil moist enough to get any flow."
Blooms have been emerging on a near-annual basis since the summer of 1995.
"It's interesting just because we're having these flip-flopping years," Ms. Johnson said.
Justin Chaffin, Ohio Sea Grant and Ohio State University Stone Laboratory research director, said he was surprised there hasn't been a stronger phosphorus load into the Maumee River and other Lake Erie tributaries from the early June rain.
Bowling Green State University researchers Tim Davis and George Bullerjahn said there has been no appreciable bloom forming yet in their primary focus area, Sandusky Bay, which typically gets blooms before Lake Erie.
Sandusky Bay is usually dominated by a different species, planktothrix, which blooms sooner than the microcystis that usually dominates the open water of Lake Erie from Toledo to Cleveland.
Mr. Davis said the lack of planktothrix in Sandusky Bay so far "is odd even though water temperatures are well above the threshold for planktothrix growth."
"We're continuing to monitor on a weekly basis now until the end of September, but usually the bloom in the bay is in full swing at this point," Mr. Davis said.
Mr. Bullerjahn agreed, but said that "this week has given us some intense downpours that may not have been accounted for in an early forecast model for the open waters of Lake Erie."
While that may not dramatically change things, it's worth watching, he said.
Doug Kane, a Heidelberg research scientist and assistant professor of biology, cautioned the public about getting too excited if this summer's bloom is indeed minimal.
"We have had a relatively dry spring and almost all the future projections are for wetter springs," Mr. Kane said. "We do not have much evidence that our actions have influenced a low loading year like this to any great extent. I continue to be very interested about what is happening in Sandusky Bay and why the bloom there has not been around the last two years."