Biological invasion is a major threat to biodiversity globally. In the scientific literature, an 'invasive' species is one that is not indigenous to a given ecosystem, and whose introduction is likely to cause harm to ecosystems and (potentially) human health and they can be introduced into new environments intentionally and/or unintentionally. In this context, recreational users play a mixed role. For instance, anglers and owners of pleasure boats may contribute to the spread of invasives as the plants can become stuck on propellers. However, these same users can also help to reduce invasions by monitoring conditions in lakes, removing exotic plants from lakes, and/or taking particular precautions to limit their spread. While the advantages of involving users in the management of recreation and/or conservation of natural sites is increasingly recognized (Granek, Madin et al. 2008, Newsome, Stender et al. 2016), it has yet to be examined in the context of complex environmental issues such as the spread of weeds in lakes.