This article in NSTA’s November 2016 issue of The Science Teacher describes a set of activities that engage students in three-dimensional learning by using diatom bioassessments to assess water quality and biodiversity in a variety of local aquatic ecosystems. Student work is guided by the essential question, “How does living in the Anthropocene affect the integrity of aquatic ecosystems?” After completing two pre-assessment activities to become familiar with diatom bioassessments and anthropogenic sources of pollution in their own neighborhoods, students design and carry out their own local investigations. Students collect and analyze data, obtain information from primary sources, and finally, assess how human activity impacts local water quality. A variety of assessments are suggested and a generalized assessment rubric for student learning outcomes is provided. The activities are supported with a list of online materials, including a simulation (SimRiver - http://www.u-gakugei.ac.jp/~diatom/en/ ) which is reviewed in a separate NGSS@NSTA Hub entry.