Harmful Algal Blooms, Hypoxia, and Nutrients Research Webinar Series
Advancing Nutrient Solutions for Estuary Management
Wednesday, February 25, 2026 from 2:00 to 3:00 p.m. EST
Developing Dissolved Oxygen Criteria to Protect Propagation of Atlantic Sturgeon in Tidal Fresh Delaware River - Jim Hagy (EPA Office of Water)
For decades, dissolved oxygen (DO) levels in the tidal-fresh Delaware River have been too low to support propagation of migratory fish, including the endangered Atlantic Sturgeon. In 2022, EPA determined that propagation of oxygen-sensitive migratory fish was an attainable use. Following an intensive period of method development and related policy development, EPA proposed new protective DO criteria in late 2023. EPA finalized the criteria in September 2025. This presentation will describe the physiologically-based cohort model and other aspects of the technical approach that EPA developed to support the rule.
Optimizing Nutrient Reductions Across the Long Island Sound Basin - Naomi Detenbeck (EPA’s Office of Applied Science and Environmental Solutions)
This presentation provides an overview of the updates to EPA’s River Basin Export Reduction Optimization Support Tool (RBEROST); a description of linkages to source loads from the USGS dynamic SPARROW model for North Shore watersheds and a groundwater-based model for loads for South Shore watersheds; and preliminary results. RBEROST is designed to enable stakeholders to identify cost-effective solutions to meet watershed nutrient loading targets, considering potential upgrades to septic systems or wastewater treatment plants, implementation of stormwater best management practices or agricultural conservation practices, and restoration of riparian zones. EPA previously released two static versions of RBEROST and is preparing to release an expanded, dynamic version.
Presenters and Moderator
Jim Hagy, EPA Office of Water
Dr. Hagy is a coastal environmental scientist in EPA’s Office of Water who has conducted scientific research and supported water quality management and policy development related to nutrients, eutrophication, and hypoxia in U.S. coastal waters. His research has addressed science and policy throughout the United States, with particular focus on Chesapeake Bay, the Gulf Coast, and recently Long Island Sound and the tidal-fresh Delaware River. Dr. Hagy’s recent work provided the technical basis for revised dissolved oxygen criteria for the tidal fresh Delaware River, which EPA promulgated in September 2025.
Naomi Detenbeck, EPA Office of Applied Science and Environmental Solutions
Dr. Detenbeck is an ecologist at EPA’s OASES Coastal Science Solutions Division in Narragansett, RI. Her current research is focused on the development and application of decision-support tools for watershed management (WMOST, RBEROST), refinement of spatial statistical temperature models for evaluating restoration options, and development of EPA’s Estuary Data Mapper. Her past research has included work on biogeochemistry, wetlands, landscape ecology, nutrient criteria development, and watershed classification. She holds a M.S. and Ph.D. in Ecology from the University of Minnesota.
Moderators:
- Brenda Rashleigh, EPA Office of Applied Science and Environmental Solutions
- Brenna Friday, EPA Office of Water
About the Webinar Series
Hosted by EPA, this free webinar series is focused on communicating the latest, cutting-edge research related to nutrients and the priority impacts of nutrient pollution: harmful algal blooms (HABs) and hypoxia.
Topics will include regional priorities; regulatory updates; and cutting-edge EPA research related to monitoring and forecasting, prevention, control, and response.
Webinars are typically held bimonthly from 2 to 3 p.m. ET on the last Wednesday of the month. Additional information and registration will be posted closer to the scheduled date and as they become available.
Past Webinar Recordings
Links to closed-captioned recordings of past webinars hosted on EPA's YouTube channel are available below. Certificates cannot be provided for watching the webinar recordings.