Challenges of managing harmful algal blooms in US drinking water systems

Inland freshwater harmful algal blooms are a growing threat to drinking water worldwide. Here we present the results of a national survey of how drinking water managers experience and perceive both nuisance harmful algal blooms and toxic harmful algal blooms (TABs) (N = 335) in the United States. We find that previous experience with harmful algal blooms increases drinking water systems’ planning and preparation. However, unexpectedly, we also find that (1) water managers who experienced TABs rate them as more difficult to manage than do those with no previous TAB experience, and (2) managers in systems that experience TABs become increasingly reliant on internal resources to respond to TABs once they occur rather than reaching out for external sources of information and technology. This turn towards self-reliance could make the effective dissemination of state-of-the-art information and solutions more difficult among water systems and further isolate some vulnerable systems.