Estero Yerba Loca is not a widely recognized term in major geographic or encyclopedic references. The phrase combines Spanish words commonly used in toponymy: estero (a small river, stream, or estuary) and Yerba Loca, which is a vernacular name for several native Chilean plant species (e.g., Muehlenbeckia australis and Acaena magellanica) and also appears in the names of protected areas such as Yerba Loka National Park near Santiago, Chile.
Given the generic nature of the components, “Estero Yerba Loca” could plausibly refer to a minor watercourse located in a region where the plant known as yerba loca grows, possibly within or adjacent to the aforementioned national park or other rural locales in central Chile. However, without citation from authoritative geographic databases, maps, or scholarly sources, the existence, precise location, and characteristics of a watercourse bearing this name cannot be confirmed.
Therefore, the term lacks sufficient encyclopedic documentation to provide a detailed entry.