Streams are some of the most hydrologically dynamic aquatic systems on Earth’s surface. The origin of stream water sets its chemical and biophysical fingerprint, yet quantifying where water comes from in streams is challenging. This is in large part because hydrologic flowpaths are dynamic in space and time, activating during certain periods of the year in response to rainfall and snowmelt and deactivating as the terrestrial environment dries. As our weather and human water use intensify, we anticipate large scale changes to the hydrologic behavior of our river and stream networks, with anticipated ripple effects to our in-stream biological communities.  This talk provides a foundational survey about how streams get their water, with case studies from across Wisconsin.