The Mars rover, Curiosity, has found evidence that a habitable freshwater lake existed on Mars for a period of up to hundreds of thousands of years. Per the article:
Analysis of mudstones in an area known as Yellowknife Bay, located inside the rover’s Gale Crater landing site, show that fresh water pooled on the surface for tens of thousands -- or even hundreds of thousands -- of years. “The results show that the lake was definitely a habitable environment,” Curiosity lead scientist John Grotzinger, with the California Institute of Technology, told Discovery News.
Thank you for the educational article John.