Development of a HAB vulnerability index for Alaska drinking water systems

Harmful algal blooms (HABs) pose a threat to public drinking water systems through cyanotoxin production and interference with particulate removal processes. Currently, little is known about the potential vulnerability of public water systems to HABs in Alaska compared to the contiguous United States, while at the same time this region could experience the greatest change in HAB risk due to disproportionate climate change impacts. Our goal was to define which public water systems in Alaska are most vulnerable to HABs. First, we gathered geographically explicit datasets on drinking water systems (SDWIS), satellite-based HAB detection (CyAN), water quality monitoring, public and private wastewater treatment locations, watershed land cover, weather, snow and permafrost cover, and climate projections. These datasets were linked spatially via the public water system identifier, waterbody, and/or watershed (HUC12). Then, we analyzed data coverage across the 78 public water systems and developed a HAB vulnerability index. Alaska has similarities to other data-poor regions in that many geospatial datasets (e.g., high-resolution NHD, PRISM, LakeCat) are not yet accessible or require manual compilation. Further, many systems were not satellite-resolvable (10/62 lakes), and water quality monitoring data had poor coverage (2/62 lakes). Thus, we focused our vulnerability index not on a predictive HAB model but rather on the factors influencing HAB risk: drinking water system characteristics, watershed nutrient sources, current and projected climate, and potential for permafrost thaw. 

Presentation Preference: Oral

Primary Presenter: Kateri Salk, Tetra Tech (kateri.salk@gmail.com)

Authors:

Hannah Ferriby, Tetra Tech  (hannah.ferriby@tetratech.com)

Michelle Ryan, Tetra Tech  (michelle.ryan@tetratech.com)

Michael Pennino, Environmental Protection Agency  (pennino.michael@epa.gov)