Assessing the Accuracy of Citizen Scientist Reported Measurements for Agrichemical Contaminants.

Citizen science is a research tool capable of addressing major environmental challenges, including contamination of water resources by agrichemicals, such as nutrients and pesticides. The objectives of this study were (1) to identify the proportion of accurate observations by citizen scientists using rapid assessment water quality tools, and (2) to characterize how a user's prior experience with water quality tools was associated with the accuracy of citizen scientists. To achieve these objectives, we conducted group testing with over 136 citizen scientists and compared their results from water quality testing of water samples to results obtained using laboratory analytical methods. Following brief training, we observed that accuracy of reported results varies based on the user's experience level where experienced and expert users shared consistent and reliable measurements. Where erroneous measures were reported, citizen scientists tend to overestimate contaminant concentrations when using colorimetric water quality tools. Additionally, we identified differences in accuracy related to the types of water quality assessment tools used by citizen scientists from each experience group. This study demonstrates the importance of evaluating participant background experience in designing citizen science campaigns.