Bloom Index

The bloom index developed by NOAA measures the severity of an algal bloom based on the biomass of harmful algae and the duration of the bloom. The size of the bloom is largely unrelated to its severity. Some amount of algae in Lake Erie is considered normal and even healthy, because algae provides food for valuable fish species. Blooms that produce toxins, however, are cause for concern and are reflected in the bloom index. Blooms with an index above 5 are considered potentially harmful.

How was it scored?

Bloom index was used as an indicator in the Western Lake Erie lake analysis. This index is published every year and was developed by NOAA, Heidelberg University, University of Michigan-NCSU-GLERL, and LimnoTech. The index is based on the amount of biomass over the peak 30 days of the bloom. The bloom index value was converted to the 100-point report card score scale and the single value was used for the overall region score for all regions in Lake Erie.

Blue-green algae growing in the Western Lake Erie Basin. Pphoto by Stuart Rankin via Flick CC BY-NC.