“…We previously reported a new algorithm for scalable river network-based assessment that completes a multistep statistical analysis over stream chemistry data and solves significant statistical challenges in terms of stream network analysis. 25 Sampling sites are clustered based on probability models over weighted river network systems. Although the tool (i.e., GeoNet) cannot yet be used to discover unknown spill incidents automatically, we show a first step in that direction here by demonstrating its utility in detecting spills in PA that have already been reported.…”