The wetlands are part of the Las Vegas Wash, a natural drain from the Las Vegas Valley to the Colorado River (now Lake Mead) The marsh is mostly dry except for run off from sprinkler systems these days, but one little rain storm, and it's a flash flood. Some times just 15 minutes of rain will flood the lower end of the valley. (where the marsh is) A friend of mine lost his Tiger 2 in the marsh, and they had to dig 18 inches to get the motor out!! That nasty black mud too!!