Which term designates a bed or channel that carries stagnant, dirty, or salt water under the influence of tides?

• A. Arroyo
• B. Bay
• C. Estero
• D. Estuary

Answer: (C)

Estero is the tidal waterway term used for a bed or channel that carries saltwater under the influence of tides. In coastal mapping, an estero describes a shallow, often muddy channel that exchanges with the sea as tides rise and fall, sometimes appearing stagnant or dirty between movements of the water. This fits the idea of a watercourse that moves saltwater with the tides, rather than a broader tidal area or a dry desert channel. An arroyo is typically dry or intermittent in arid regions, a bay is a broad coastal inlet, and an estuary refers to the larger zone where river water mixes with seawater, not the specific channel itself. So estero best matches the described feature.