Another severe algal bloom will hit western Lake Erie later this summer, according to environmental scientists from the University of Michigan and the National Oceanic and Atmospheric Administration.
Last August, high levels of cyanobacteria shut down Toledo's drinking water supply.
Heavy rains in June have set up conditions for another severe bloom, ranking between an 8.1 and 9.5 on a 10-point scale. Any bloom greater than a 5.0 is of concern. Scientists say they can't predict whether there will be another "Toledo event," as that depends on how the bloom develops.
This year's bloom will be second in severity after the record-setting 2011 algal bloom.
"We're looking at potentially the second-worst bloom, after 2011, worse than 2013. We're expecting a bloom more severe than 2014 from a biomass perspective, as compared to any issues from a water treatment perspective," says Rick Stumpf, an oceanographer with the National Center for Coastal Ocean Science, NOAA.
The recurring harmful algal blooms are caused by the agricultural use of phosphorous in the Maumee watershed. Until those phosphorous levels are reduced, scientists say, the blooms will continue.
This is the fourth year that NOAA has offered an algae forecast for western Lake Erie. The forecast allows water treatment plants to reduce risk by stocking up on treatment chemicals and charcoal.
NOAA offers a detailed five-day harmful algal blooms tracker based on remote sensing, water monitoring, and hydrodynamic modeling.