October marked the end of the summer harmful algal bloom (HAB) season on Lake Erie. The 2018 Microcystis bloom had a final severity index (SI) of 3.6, much milder than last year's severe bloom with an SI of 8. The severity index captures the amount of bloom biomass over the peak 30 days of the bloom. The bloom was smaller than the July forecast with an SI of 6, and all models overestimated the bloom to some degree (a range from 4.9 to 7.8). The reasons for the overestimates of the several models will be reviewed and updated along with continuing a strategy for creating an ensemble forecast based on past experience.

For the full final bulletin and seasonal assessment, click here.