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Using satellite imagery and national surveys to identify lakes at-risk for toxic cyanobacteria blooms in the U.S..
Citation:
Handler, A., J. Compton, Ryan A Hill, S. Leibowitz, AND B. Schaeffer. Using satellite imagery and national surveys to identify lakes at-risk for toxic cyanobacteria blooms in the U.S.. Meeting with Florida Department of Environmental Protection, virtual, FL, August 30, 2022.
Impact/Purpose:
Cyanobacterial harmful algal blooms (CHABs) can produce toxins which impair freshwater ecosystems used for drinking water, recreation, and habitat for aquatic biota. With reports of CHABs increasing, water managers need information about how to prioritize lake monitoring. This presentation for the Florida Chief Science Officer and Florida Department of Environmental Protection highlights the results of national modeling of lake CHABs risk by combining data from the Cyanobacteria Assessment Network satellite imagery on CHABS and the USEPA’s National Lakes Assessment field algal data. This project illustrates EPA’s work that strives to address the needs of water resource managers as it relates to setting monitoring priorities for CHABs. The audience for the presentation includes the State of Florida’s Chief Science Officer as well as leaders of the Florida DEP including the Blue-Green Algae Task Force, Division of Environmental Assessment and Restoration, Office of Environmental Accountability and Transparency. Their knowledge and feedback about this analysis is invaluable to creating a product that helps inform lake CHABs risk.
Description:
Algal blooms caused by toxin-producing cyanobacteria are a threat to global water resources and human health. Water resource managers need tools that identify which lakes are at risk of toxic cyanobacteria blooms. We address this need by using Cyanobacteria Assessment Network satellite imagery and US EPA National Lakes Assessment field surveys to model the probability of large lakes exceeding lower and higher demonstration thresholds of microcystin toxin, cyanobacteria, and chlorophyll a. For every satellite-derived Cyanobacteria Index (CI_cyano) increase of 0.01 (CI_cyano/km2) the odds of exceeding the six thresholds increased by 23–54%. When applied to all 2,192 satellite monitored lakes, the models identified lakes with ≥75% probability of exceeding the lower or higher thresholds as less than 336 and less than 70 lakes, respectively. Our approach identified lakes that are at higher risk of experiencing toxic algal blooms and may require additional monitoring. We compiled lake water chemistry, lake morphology, watershed characteristics, and basin climate data to evaluate potential predictors of blooms. In addition, we compared models with and without lake physical and chemical data to assess the need for in-lake information to determine lakes at higher risk for experiencing blooms. These approaches are a critical advancement in using national datasets to determine which lakes may require additional field monitoring and management priorities.