A novel index reveals disconnects between recreational harmful algal bloom exposure risks and responses among U.S. states

Recreational and occupational contact with freshwater harmful algal blooms (HABs) pose human health and economic risks worldwide. Individual U.S. states control monitoring, reporting, and mitigation of recreational exposure to HABs. We surveyed states to catalog responses to HAB problems. We used this data to develop a state-specific HAB response index (HABRI) and compared it to HAB risks derived from empirical nation-wide data and per capita state environmental management and public health spending. States varied in regulations, reporting, monitoring, communication, and mitigation. The HABRI was not correlated with empirically based risk. Several states had no limits on toxin exposure or limits that were higher than recommended by the USEPA or World Health Organization. Other states did not provide public signage or notification when HABs were occurring and recreation could be hazardous. Increased federal involvement, communication among states, and state and federal legislation could minimize this variation and positively influence responses. We identify best practices for addressing HABs in our study that could provide guidance to authorities in any part of the world while developing new programs or enhancing existing efforts.