Its tributaries are the streams La Leonera and Chorrillo del Plomo ,as well as a number of springs that well up near the main river bed and not only contribute water volume, but also form numerous cascades.

Since the Yerba Loca area varies in altitude from 900 to 5,500 meters above sea level, the flora is richly varied (actually, the Sanctuary's name derives from a herb which is found in great quantities in the area). Forestry species such as bollen, litre, quillay and lun are abundant up to 1,300 meters above sea level.

Between 1,300 and 2,000 meters above sea level is found the olivillo de la cordillera (miniature olive tree of the Cordillera), which is in danger of extinction in the Metropolitan Region. Also, in the Villa Paulina sector there are woods with introduced species (introduced both by the local inhabitants and Conaf) which have adapted to Andean conditions. These are certain conifers such as cypresses and Oregon pines, as well as poplars, elms and eucalyptus trees.

There can be no doubt that birds are everywhere to be seen in the Sanctuary. The most common species are turtle doves and the peucos and cernicalos, among the birds of prey. At higher altitudes, the eagles and condors are lords of the sky.

The rest of the representatives of the animal world, namely mammals and reptiles, are not so abundant. The animal genus most widely represented in the Sanctuary is Rodentia, whose most representative specimens are the cururo, the degu and Darwin's "large eared" mouse. ("Nature Sanctuary" D.S. Nº 937)

Activities that are possible to do are:

- Horseriding in different natural settings.

- Bird Watching, including migration, behavior and habitats.

- Photography, including shots of interior and exterior views in authorized places.

- Flora and fauna observation - different animal and plant species native to the area may be admired.

Source: www.sernatur.cl