NOAA and its research partners are forecasting a mild to moderate harmful algal bloom (HAB) in western Lake Erie this summer. This year's bloom is expected to measure 3 on the HAB severity index, with a potential range of 2-4.
The HAB severity index is based on the bloom's biomass (the amount of algae) during the peak 30 days of the bloom. Moderate blooms have an index of 3-5, while an index above 5 indicates more severe HABs. Blooms over 7 are particularly severe, with extensive scum formation and bloom coverage affecting the lake.
Stone Laboratory and Ohio Sea Grant at The Ohio State University hosted a live web event today for NOAA's annual official HABS forecast for western Lake Erie.
Lake Erie HABs consisting of cyanobacteria (i.e. blue-green algae) are capable of producing microcystin, a known liver toxin which poses a risk to human and wildlife health. Such blooms can lead cities and local governments to add more treatment to drinking water and close beaches. HABs also harm local economies by preventing people from fishing, swimming, boating and visiting the shoreline, with annual economic impacts estimated at over $70 million for the Lake Erie region.
The size of a HAB is not necessarily an indication of how toxic it is. Each algal bloom is unique in terms of size, toxicity and ultimately its impact on local communities. NOAA continues to develop new tools to detect and predict how toxic blooms will be.
"Harmful algal bloom forecasts are critically important for communities around Lake Erie to plan and prepare, and are a key part of NOAA's scientific service to the nation," said Nicole LeBoeuf, director of NOAA's National Ocean Service. "The Great Lakes are a driver of economic activity throughout the region and environmental outlooks can help ensure the hazards of toxic algae are well understood to protect public health."
NOAA's National Centers for Coastal Ocean Science's (NCCOS) Lake Erie HAB Forecast website provides predictions and visualizations of the bloom's location and movement on the lake's surface, as well as where the bloom is located within the water column. This information is especially helpful to water treatment plant operators because intake structures are usually located below the surface, so the risk of toxins in their source water may be greater when these cells sink.
The field observations used for monitoring and modeling are collected in partnership with a number of NOAA offices, including its Ohio River Forecast Center, NCCOS, Great Lakes Environmental Research Laboratory and Cooperative Institute for Great Lakes Research, as well as Ohio Sea Grant, Ohio State's Stone Laboratory, The University of Toledo and Ohio Environmental Protection Agency.
NOAA expects to see a visible bloom by early July. How long it lasts will depend on the frequency of high winds in September, which cannot be predicted this far in advance. Most of the bloom will remain in areas of the lake's western basin. The central basin of the lake is usually unaffected until later in the season, although localized blooms may occur around some of the rivers after summer rainstorms.
NOAA will issue a seasonal forecast update in late July based on observed nutrient loads from the Maumee River watershed into the western basin. In addition to the early season projections, NOAA also issues HAB forecasts during the bloom season with details about the bloom's current extent. NOAA also provides five-day outlooks, which are predictions of where the bloom will travel and the concentrations of blue-green algae which are likely to be seen, allowing local authorities to make informed management decisions.
