Abstract
Aquatic invasive species (AIS) create costly and detrimental effects when they become established. Recognition of these severe negative impacts in the United States reached a critical threshold in 1990 with the federal passage of the Nonindigenous Aquatic Nuisance Prevention and Control Act, which created six regional panels, the national Aquatic Nuisance Species Task Force, and incentivized state-level AIS planning. The management of the Ohio River basin fell under the Mississippi River Basin Panel and the state-led Mississippi Interstate Cooperative Resource Association, which collectively developed a joint action plan in 2010 to prevent, contain, and manage aquatic nuisance and invasive species. Similarly, except for West Virginia, all Ohio River basin states created aquatic nuisance species plans between 1999 and 2021. We use the USGS Nonindigenous Aquatic Species (NAS) database to examine how these legislative and planning milestones have influenced the rate of new NAS arrivals and the spread of existing and new NAS. Arrival and spread of NAS were assessed at the HUC-8 scale (8-digit hydrological unit code) along the Ohio, Wabash, Cumberland, Alleghany, Monongahela, and Tennessee rivers. We found a near-linear increase of new NAS across all rivers and no apparent change related to policy milestones. We also found that most NAS species (35–55%) remained local, not spreading beyond the HUC they were first detected in, while less than 10% spread to all HUCs within a river. Establishing coordinated local and regional monitoring programs will help to contain future invasive species.