Lake Erie Experiences ‘Severe’ Algae Bloom in 2017

Source: The Hannah Report

The harmful algal bloom (HAB) that formed on Lake Erie this year had a severity index (SI) of eight, making it a “severe bloom” roughly equivalent to the 2013 HAB, which was the third worst bloom observed this century, according to a seasonal assessment from the National Oceanic and Atmospheric Administration (NOAA).

According to NOAA’s HAB bulletin, the worst blooms this century were observed in 2011 (SI of 10) and 2015 (SI of 10.5).

“During the week following Sept. 20, the bloom covered a maximum area of 1,000 square miles from Toledo to the Ontario coast, reaching the mouth of the Detroit River. During that week, scum covered up to 280 square miles of the Western Basin,” NOAA said. “For comparison, the 2015 bloom covered over 4,000 square miles of the lake at its maximum extent, yet had similar scum coverage at any one time to 2017. In the Western Lake Erie Basin, the bloom biomass was less toxic than several of the recent bloom years.”

NOAA said the 2017 bloom had a “double peak,” with one in August followed by a decrease in biomass and then a strong reappearance in mid-September.

“The densest bloom in August was mostly in the center of the Western Basin, while the bloom impacted more shorelines in September. Isolated pockets of the Microcystis bloom persisted into late October along the Michigan shoreline,” NOAA said. “Heavy rains in May and late June resulted in high discharge from the Maumee River. The high concentration of phosphorous in the river combined with the high discharge produced conditions favorable for the bloom.”