How’s the water in Saginaw Bay? Sometimes, in the summer, it turns green along the shoreline due to harmful algal blooms, or HABs. These blooms can be filled with tiny cyanobacteria that produce toxins as they live and die. You may have heard of HABs occurring in Lake Erie. They became bad enough in 2014 to shut down the water supply in the city of Toledo, Ohio, for more than two days.
Such a crisis hasn’t happened in the Saginaw Bay area. And it hasn’t happened in Toledo since 2014 due to measures including an Experimental Lake Erie Harmful Algal Bloom (HAB) Tracker. That tool is primarily used by people at water treatment plants to help monitor conditions and make sure the water supply remains safe.
Does Saginaw Bay need a similar tracking system, to issue forecasts and inform the public about beach conditions, for instance? Researchers have been exploring that idea with groups in the region, including at summer 2019 workshops with people who use the bay for activities like swimming, fishing and boating.
A new tracker for Saginaw Bay would build on recent advances by the US National Oceanic and Atmospheric Administration (NOAA), says Mark Rowe, a research physical scientist with the Great Lakes Environmental Research Lab (GLERL), an arm of NOAA located in Ann Arbor, Michigan.
In July 2019, NOAA began operating an improved three-dimensional forecast model called the Lake Michigan-Huron Operational Forecast System. The model provides real-time forecasts of up to five days for water circulation, temperature and levels. NOAA also introduced a cyanobacterial index in 2017 that measures HAB intensity using higher-quality images from the European Space Agency’s Sentinel-3 satellite.
“This is an opportunity to find out if we can leverage those new things to produce some useful products for stakeholders in the Saginaw Bay region,” Rowe says.
The state’s environmental agency, the Michigan Department of Environment, Great Lakes, and Energy, also monitors nearshore beach areas and drinking water treatment plants along with the Michigan Department of Health and Human Services.
Freshwater blue-green algae or cyanobacteria can produce toxins called microcystins that make people sick. In Saginaw Bay, the blooms are fed by the typical culprits: nutrients contained in runoff from farms, urban areas and discharges from wastewater treatment plants.
Researchers say microcystins are present in Saginaw Bay from the regular season of mid-July through September, but in lower concentrations than those measured in Lake Erie.
Recreational advisory levels for microcystins are rarely exceeded in Saginaw Bay. Microcystin concentrations often exceed drinking water advisory levels in the inner bay, but drinking water intakes are located north of the affected area.
Most Saginaw Bay blooms are limited to a five-mile stretch along the near shore of the inner bay, says Tom Johengen, director of Michigan Sea Grant, a project of the University of Michigan, Michigan State University and NOAA. “That’s the portion of the bay that’s most directly influenced by the Saginaw River,” Johengen adds.
The Saginaw River and Bay was designated as an Area of Concern in the 1980s and actions are ongoing to deal with a variety of issues, including algae.
Assessing the Need
At the summer workshops, researchers heard that there wasn’t a “strong need” for a separate Saginaw Bay HAB tracker, Rowe said.
“We don’t want to raise public awareness on a problem that’s maybe not really a problem,” he added.
But Rowe says monitoring and discussions in the community are ongoing, and some informational products on Saginaw Bay algae may be introduced in the future.
“At this point, we’re planning to continue doing the research for another year,” Rowe said. “We’re interested in looking at transport events (like wind) that may carry algae from the inner bay, along the coast, and affect drinking water intakes and communities and state parks.”
The Saginaw Bay work is a small part of a larger, ongoing project funded by the US Great Lakes Restoration Initiative. A $1.5 million annual grant has been used for monitoring in Lake Erie and Saginaw Bay, the Lake Erie tracker and advanced technologies for Lake Erie sampling.