Public participation in groundwater projects is increasing, however, the efficacy of the data collected in such studies, is not well‐documented in the literature. In this study, the authors describe a citizen science project focused on measuring and recording groundwater levels in an aquifer and evaluate whether the groundwater data collected by the participants are trustworthy. A total of 31 participants were initially recruited to measure and record groundwater levels from 29 monitoring wells on a barrier island. Following recruitment, the authors provided training to the citizen scientists by introducing groundwater concepts, and showing the participants how to measure, record and report groundwater level data (over an 81‐day period) with an electronic water level meter. The water level data recorded by the citizen scientists (i.e., 35 time series datasets with over 450 unique measurements) were then compared to high frequency data recorded by automated water level loggers that were already deployed in the groundwater monitoring wells to assess the trustworthiness of the data. Trustworthiness was evaluated using measures of reliability (i.e., consistency in measuring the same thing), validity (i.e., degree to which results are truthful), and other standard graphical and statistical techniques. The results suggest that with proper training, guidance, and motivation, citizen scientists can collect trustworthy groundwater level data that could be useful for monitoring the sustainability of aquifers and managing of groundwater levels. It is noted however, that such positive outcomes require significant investments of time and effort on the part of the project managers.