Lake Erie Bloom Severity Index

Annual values for the years 2000 to 2024 representing the severity of the harmful algal bloom in the western basin of Lake Erie according to an index scaled from 0 to 10, based on satellite-based bloom observations. Following the 2024 Microcystis bloom in western Lake Erie, NOAA’s National Centers for Coastal Ocean Science HAB Monitoring Program reprocessed the satellite remote sensing time series used to monitor the severity and impacts of annually occurring cyanobacteria (Microcystis) HABs. The satellite reprocessing included new calibrations and improved algorithms, generating a more consistent data set for HAB monitoring in Lake Erie. You can find more information about the updated time series here. The new time series was used to re-evaluate overall cyanobacteria bloom severity index (SI) for Lake Erie. The SI is based on the quantity (biomass) of the bloom over a sustained 30 day period and is scaled to the minimum observed bloom biomass (2005) and maximum observed bloom biomass (2015) to date. More information about the SI can be found in Stumpf et al. 2016 (https://doi.org/10.1016/j.jglr.2016.08.006). More information