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Lake Erie Harmful Algal Bloom Forecasts Now Operational

New changes mark NOAA’s commitment to ensuring that high quality forecasts are delivered reliably for years to come.
Lake Erie Harmful Algal Bloom
A man holds a glass of water from Lake Erie during a harmful algal bloom with the drinking water supply intake for the city of Toledo in the background. Photo copyright Dave Zapotosky.

July is approaching – the season when harmful algal blooms (HABs) may start to form in Lake Erie. As in past years, NOAA will provide HAB forecasts that support bloom response efforts and will deliver the forecasts in semi-weekly bulletins. However, this year is special because the bulletins have moved out of the experimental research phase and have been incorporated as official NOAA forecasts. This transition is a culmination of years of research and includes dedicated resources for maintaining the forecast system, technical support, and backup servers. All of these changes mark NOAA’s commitment to ensuring that high quality forecasts are delivered reliably for years to come.

We will issue NOAA’s first official HAB forecast bulletin on July 3 and then issue twice-weekly bulletins during a bloom event and until the season is over.

Harmful algal blooms in Lake Erie
HABs are a recurring problem in Lake Erie. They can produce toxins that need to be removed from water before it is safe to drink. The blooms also form surface scums that can impact regional tourism, beach recreation, and recreational and commercial fishing. Learn more in this story map.

What does NOAA forecast in the bulletins?
NOAA uses satellite imagery to monitor HABs in Lake Erie from space, and water samples collected in the field provide eyes on the ground. The satellite imagery is integrated into a computer model of Lake Erie circulation in order to forecast where the bloom may move over the next 3 days. Based on the observed and predicted wind conditions, NOAA forecasts whether the bloom may be forming a scum at the water’s surface or become mixed in the water column where it might impact drinking water supplies. Every year in the fall, as the water temperatures become too cold for the algae cells to survive, NOAA also forecasts the decline of the bloom.

Putting the forecast into action
Coastal resource managers, public water suppliers, and public health officials can use the bulletins to support their response efforts including planning water treatments to protect drinking water and coordinating advisories to keep people and pets safe. The bulletins can also help people plan their activities on the water. For instance, the bulletin can help boaters plan a trip that avoids the bloom. The bulletins are emailed to subscribers and posted to the website: To subscribe, go to

Please contact with questions.

Revised: 10/15/2013
NOAA / National Ocean Service
Web site owner: Center for Operational Oceanographic Products and Services