The National Oceanic & Atmospheric Administration (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 effects of the cyanobacterial blooms include a higher cost for cities and local governments to treat their drinking water, as well as risk to swimmers in high concentration areas, and a nuisance to boaters when blooms form. These effects will vary in locations and severity with winds, and will peak in September, according to the report.

The blame for the high bloom is being put on heavy June rains causing heavy nutrient runoff into the lake basin. The bloom is 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 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.

“While we are forecasting a severe bloom, much of the lake will be fine most of the time. The bloom will develop from west to east in the Lake Erie Western Basin, beginning this month. It is important to note that these effects will vary with winds, and will peak in September,” said Richard Stumpf, Ph.D., NOAA’s ecological forecasting applied research lead at NCCOS, who formally presented the forecast in a media event and science presentation at Ohio State University’s Stone Lab on Lake Erie this week.

“This is the fourth seasonal harmful algal bloom outlook for Lake Erie that NOAA has issued,” said Holly Bamford, Ph.D., assistant NOAA administrator for the National Ocean Service performing duties of the assistant secretary of commerce for conservation and management. “NOAA’s ecological forecasting initiative, including this Lake Erie seasonal forecast, the NOAA weekly HAB bulletin, and the experimental early season HABs Tracker, provide science-based information that water managers, public health officials, and others need to make critical decisions to protect the health of their communities, understand environmental impacts, and mitigate damages to recreational activities that are a vital part of the region’s economy.”

This image shows the extent of the Lake Erie algal bloom at its height in 2013 (top) and 2014 (bottom). Orange and red show concentrations that may cause scums and other issues. Different areas are affected in the two years because of wind patterns. The data came from NASA's Aqua satellite and was analyzed by NOAA's Center for Coastal Ocean Science. (Credit: NOAA)

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, 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.

“Last summer’s Toledo water crisis was a wake-up call to the serious nature of harmful algal blooms in America’s waters,” said Jeff Reutter, Ph.D., senior advisor to, and former director of, The Ohio State University’s Sea Grant program and Stone Laboratory. “This forecast once again focuses attention on this issue, and the urgent need to take action to address the problems caused by excessive amounts of nutrients from fertilizer, manure and sewage flowing into our lakes and streams.”