A defining characteristic of the Great Basin's hydrology is that it is an endorheic basin, with no outflow to the ocean.

The Great Basin is classified as an endorheic basin, which means it has no natural drainage to the ocean. Water within the basin, such as rivers and streams, either evaporates due to the region's arid climate or is absorbed by the ground. This creates closed water systems like the Great Salt Lake, where water collects but does not flow out. This unique hydrological characteristic shapes the Great Basin’s ecosystems, leading to salt flats and influencing the region's overall dry, desert-like environment.