What characterizes an ephemeral stream?

An ephemeral stream is characterized by its only carrying water intermittently, specifically during and immediately following precipitation events. These streams typically do not have a continuous flow and can go dry for extended periods, often aligning with the seasonal weather conditions of the area. The correct answer highlights that these streams primarily carry stormwater, which means that they respond directly to rainfall, resulting in flowing water only during times of precipitation. When there is no rain, the stream may completely dry up, differentiating it from perennial streams, which maintain a constant flow.

This understanding emphasizes the nature of ephemeral streams as temporary conduits for water, which contrasts with other options that suggest continuous flow or water presence. For instance, streams that carry water year-round or contain water throughout the summer do not fit the definition of an ephemeral stream, as they suggest a more persistent water presence. Similarly, holding water only during droughts does not describe the operational characteristics of ephemeral streams, as they become active in response to rain rather than dry conditions.