Harmful Algal Blooms, Hypoxia, and Nutrients Research Webinar Series

Wednesday, September 24, 2025 from 2:00 – 3:00 p.m. ET

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1. Using predicted chlorophyll-a and cyanobacteria concentrations in surface waters to characterize harmful algal bloom impacts on US drinking water quality -  Meredith Brehob (ORISE), and Michael Pennino, U.S. EPA Office of Research and Development

   In this presentation, we explore innovative approaches to predicting harmful algal blooms and their impacts on drinking water quality across lakes in the conterminous United States. We paired survey data with contextual nutrient, landscape, lake, and climate data to predict nutrient and chlorophyll-a concentrations in lakes. Combining lake predictions with drinking water system operation and violation data allowed us to explore the impacts of harmful algal blooms on drinking water and develop a simplified risk metric for determining where drinking water is most vulnerable to the effects of HABs.

2. Predicting cyanobacteria abundance and microcystin detection in 125,000 on-network US lakes - Melanie Reynolds, U.S. EPA Office of Research and Development (ORISE) 

   With increasing concerns about freshwater cyanobacteria blooms, there is a need to identify which waterbodies are at risk for developing blooms, especially those that produce cyanotoxins. We developed spatial statistical models based on national lake characteristics, nutrient input and other watershed data to determine which factors best explain the presence of harmful cyanobacterial blooms. These models can help identify which lakes are more vulnerable to blooms and in need of additional monitoring or communicating with communities near high-risk lakes. 

Presenters and Moderator 

• Meredith Brehob, EPA Office of Research and Development (ORISE)

  Meredith Brehob is an aquatic ecologist with an ORISE fellowship at the U.S. EPA’s Office of Research and Development. In this role, she works on applying national data to assess nutrient impacts on freshwater ecosystems and drinking water systems. Meredith has a Master of Science degree in Natural Resources and Environmental Science from the University of Nevada, Reno.

• Michael Pennino, EPA Office of Research and Development 

  Michael, an Ecologist with EPA’s Office of Research and Development in Washington, DC, focuses his research on understanding spatial and temporal trends for indicators of environmental quality and human health. Currently, Michael is leading projects assessing impacts of wildfires, harmful algal blooms, urban best management practices, and other factors that influence nitrate and other contaminants in drinking water and source waters. He holds a B.A. from Oberlin College (2005) and a Ph.D. from the University of Maryland, Baltimore County (2014). 

• Melanie Reynolds, EPA Office of Research and Development (ORISE)

  Melanie is a post-masters ORISE fellow within the Pacific Ecological Systems Division in Corvallis, working with Jana Compton and Ryan Hill. She earned her master’s degree last year from the University of Maryland, studying geography with a focus on remote sensing and deforestation monitoring.

• Moderator: Jana Compton, EPA Office of Research and Development 

  Jana Compton is a biogeochemist with EPA’s Pacific Ecological Systems Division, focusing on the influence of watershed characteristics and nutrient use on surface and groundwater quality.