GIBRALTAR ISLAND - Researchers' early forecasts are projecting a harmful algal bloom this summer likely to exceed the severity of last year in western Lake Erie, although there is still some uncertainty.
The severity of the blooms depends on the amount of phosphorus drained into the lake, most notably from the Maumee River during the loading season, which runs from March 1 to July 31, according to Laura Johnson, director of the National Center for Water Quality Research at Heidelberg University.
“We monitor the Maumee River as part of our tributary loading program, where we’re monitoring water quality at 18 different stations — at each one of these sites three times a day,” Johnson said. “Our technicians collect these samples every week and then analyze them for most of the major nutrients.”
For projecting harmful algal blooms in Lake Erie, researchers look at the levels of “total bioavailable phosphorus,” which refers to a combination of all dissolved reactive phosphorus and the portion of its particulate form that harmful blue-green algae can feed on to bloom.
“Each one of these monitoring stations is co-located with (United States Geological Survey) sites, so we get water quality and we use the USGS data to get the discharge and flow measurements,” Johnson said. “We put the two together to get our loading.”
One of the primary factors in the amount of total bioavailable phosphorus loading into the lake is precipitation, as significant rainfall during the loading season can lead to larger amounts of phosphorus runoff being drained into the lake.
In June 2015, the western Lake Erie basin saw a record high month of rain and the year’s harmful algal blooms were the most severe ever recorded.
The drought conditions in spring and summer 2016 led to much milder blooms the following year, the lowest since 2012.
Researchers at Heidelberg, funded by and conducted along with the National Oceanic and Atmospheric Administration, or NOAA, make their forecasts based on a combination of the measurements taken to date and as well as past data.
“For places like the Maumee and the Sandusky (rivers), we have been monitoring there since 1975,” Johnson said. “So it’s a very rich data set we have here.”
Rick Stumpf, oceanographer at NOAA and lead for the Lake Erie algal bloom forecast, described the work by the NCWQR as “critical” to making the projections.
“That nutrient data is what drives all of the models that go into this,” Stumpf said.
Beginning in May, the forecast is updated weekly with the most recently updated projections, which are released in bulletins available to the public.
“In March and April, the Maumee River had discharge and phosphorus loads below average. May has been an extremely wet month, leading to large phosphorus loads from the Maumee River,” the report states. “The total spring load has now exceeded the loads observed in mild bloom years. The timing of the end of the wet weather is still uncertain, leading to uncertainty in the ultimate phosphorus load and the size of the bloom.”
The phosphorus load thus far this year has been above the pace set in last year, as well as 2012 and even 2015, through the end of May, according to the report. However, it is below levels set in 2011.
The complete report can be read online at NOAA’s National Centers for Coastal Ocean Science forecast website. The public can also subscribe for free to receive the weekly updated bulletins via email.
In early July, a final seasonal forecast will be issued from Ohio State’s Stone Laboratory on Gibraltar Island. The bulletins will then be released twice weekly and include short-term forecasts on the bloom’s location.