On July 9, NOAA and its research partners, using an ensemble modeling approach, predict that the 2015 western Lake Erie harmful algal bloom season will be among the most severe in recent years and could become the second most severe behind the record-setting 2011 bloom.The bloom will be expected to measure 8.7 on the severity index with a range from 8.1 to potentially as high as 9.5. This is more severe than the last year's 6.5, and may equal or exceed 2013, which had the second worse bloom in this century. The severity index runs from a high of 10, which corresponds to the 2011 bloom, the worst ever observed, to zero. A severity above 5.0 indicates blooms of particular concern.

The 2015 seasonal forecast uses models that translate spring nutrient loading into predicted algal blooms in the western basin of Lake Erie. After a relatively dry April and May, the heavy rains in June produced record discharge and nutrient loadings from the Maumee River, which runs through Toledo, Ohio as well as northeastern Indiana, and will result in a more severe bloom. This marks the fourth year that NOAA has issued an annual outlook for western Lake Erie.Models were developed by scientists at NOAA's National Centers for Coastal Ocean Science (NCCOS), the University of Michigan, LimnoTech, the University of Michigan Cooperative Institute for Limnology and Ecosystems Research, and the NOAA Great Lakes Environmental Research Laboratory (GLERL). The models use nutrient load data collected by Heidelberg University's National Center for Water Quality Research.

For more information contact Rick.Stumpf@noaa.gov.