The National Oceanic and Atmospheric Administration has forecasted a smaller-than-average algal bloom in Lake Erie this summer. The toxic glob comes from colonies of algae that grow out of control and produce harmful effects on people, animals and birds.
This is the second year in a row Lake Erie will experience a smaller bloom. This year’s bloom is expected to measure 3 out of 10 on the severity index, but could ultimately range between 2 and 4.5. The bloom during the 2020 season measured at a three. Blooms ranked five and above are considered severe, with those measuring over seven resulting in extensive scum coverage.
The blooms form when nutrients, like phosphorus, combine with warm water temperatures and light. According to NOAA, poor farming practices result in increased levels of phosphorus in the water due to high use of fertilizers and the presence of livestock near water supplies. Algal blooms with blue-green algae have the presence of cyanobacteria, which can produce microcystin, a liver toxin.
Why Less Algae?
The smaller blooms of the last two years are the result of a dry spring, according to Rick Stumpf, NOAA National Centers for Coastal Ocean Science’s lead scientist for the seasonal Lake Erie bloom forecast. Rainfall typically washes fertilizers off of farm fields and into the lake, via tributaries like the Maumee River, feeding the algae.
There have been some efforts to reduce agricultural phosphorus runoff, including $30 million in funding from the Ohio Department of Agriculture last year for inventions proven to reduce runoff. But Stumpf said it’s too early to tell if those measures are having an effect this year.
“Those are just now being implemented so we’ve not yet seen a shift in the concentration,” Stumpf said. “So right now, the year to year is dependent primarily upon the rainfall.”
The concentration of phosphorus remains the same as recent years, Stumpf said, which means above-average rainfall would result in a more severe bloom. But there are efforts underway to reduce runoff.
“Thanks to our partnerships with governmental agencies, academia, and state research initiatives…we are continuing to address the challenges of harmful algal blooms from all angles,” said Christopher Winslow, Ph.D., director of Ohio Sea Grant and Stone Laboratory in NOAA’s forecast report.
The size of the blooms do not indicate the toxicity of the water. Toxins in a smaller bloom could be more concentrated. Winds could concentrate or dissipate the bloom, according to NOAA. Stumpf said people, and their pets, should avoid swimming or boating near the blooms. “Unfortunately several dogs die each summer in this country by swimming in lakes that actually have toxic cyanobacteria.”
A half-million residents of Toledo, Ohio were without drinking water in 2014 after the algae infestation grew out of control.
Cyanobacteria levels are currently at low concentrations thanks to cool lake temperatures during May and June. The bloom, which will become visible later this month, will remain mostly in the western basin of the lake, though storms could create localized blooms closer to Pennsylvania in the eastern basin.
NOAA tracks the position and size of the bloom via satellite imagery. Lake Erie swimmers can check their website to determine if it’s safe to swim in their area.