Definitions for "Ephemeral streams"
Streams that flow only as the direct result of rainfall or snowmelt. They have no permanent flow.
Ephemeral waterbodies are streams, ponds, wetlands, etc. that contain water only a fraction of the time. Vernal pools and desert washes are examples. Sometime such waters are called "intermittent". As a general rule, a waterbody is NOT excluded from the CWA definition of "waters of the U.S., simply because it is intermittent.
Low places in the landscape that only flow shortly after significant rainfall. Does not have a well defined channel.