Citizen scientists can play a vital role in the first-tier screening of chemical contaminants in aquatic environments. For this to occur, the citizen scientists must be motivated and convinced to coalesce into functioning but loosely structured groups. Furthermore, the data they collect will have to be inexpensive to gather but also meaningful at fairly high levels of discrimination. Finally, the data from individual citizen scientists will have to be integrated into a large, professionally managed, and comprehensive database. We contend that all of the above criteria are already met, and in fact, other environment-related disciplines are already putting citizen scientists into action. Citizen scientists represent a collective workforce that can amass large data sets at minimal effort or cost, which can then be analyzed in an aggregate and used as a first-tier screening tool in environmental assessment.