One of Saturn’s moons, Titan, is known to have rivers and methane on its surface. It also has lakes near its poles, and what’s interesting about it is that is the only place other than Earth that has liquid water on its surface.
The only problem, however, would be that the lakes contain ultracold ethane and methane, and the temperature reaches 180°C. By taking all these factors into consideration, is hard to tell if life can exist in such extreme conditions.
As data from NASA’s Cassini spacecraft has shown, Enceladus (another of Saturn’s moons) could also contain water.