Seasonal dark streaks on Mars known as Recurring Slope Lineae (RSL) propagate down steep, warm slopes and appear to be liquid water flows. However, the mechanism behind RSL formation is controversial, and both dry granular flow and percolating water hypotheses have been proposed. To determine if water is responsible for RSL formation, I investigated similar dark streaks generated by percolating water in the McMurdo Dry Valleys (MDV) of Antarctica, an extremely cold and dry Mars analog site. The goal of this research is to identify the source of water to the MDV streaks, and to compare the MDV streaks to Martian RSL. I characterized the MDV streaks by (1) analyzing a ~30-day time-lapse video of the streaks collected on site, (2) investigating the drainage hydrology, and (3) comparing hundreds of satellite images of the streaks from 2003-2017. My results show that the MDV streaks are very different from Martian RSL, which indicates that water is not involved in RSL formation. Unlike Martian RSL, I found that MDV streaks propagate downslope at much slower rates compared to Martian RSL, and do not grow and retreat seasonally. Furthermore, MDV streaks have distinctive patterns not apparent in Martian RSLs, and rapidly darken/lighten in response to relative humidity changes. Finally, MDV streaks form in response to extremely warm summer temperatures, conditions which are unlikely to prevail on Mars. These results are important for understanding how and if liquid water occurs on Mars’ surface.