Clean water is rapidly becoming one of the most precious resources on our planet, and ecologists struggle to keep pace with the need to monitor important chemical qualities of watershed regions, industrial and municipal wastewater effluent, and aquifers, all of which have been impacted by large-scale agriculture. Historically, this work involved field sampling bodies of water and conducting most of the actual chemical measurements in fixed-location laboratories. However, the past few decades have seen a dramatic shift toward the use of multiparameter water quality probes, such as the one pictured here by GeoScientific, Ltd. This sensor includes electrochemical probes for the simultaneous field measurement of dissolved oxygen, pH, nitrate, ammonium, and conductivity. It also has the ability to conduct spectroscopic measurements of chlorophyll, algae, and rhodamine, which is a fluorescent dye sometimes added to mobile bodies of water (e.g., rivers, streams) to monitor flow dynamics.