This site is located in the department of San Rafael, 8 kilometres from the town of El Nihuil, covering an area of 350 hectares.
The marshlands and the lake formed by two main and several smaller branches of the Atuel River run through the plain to reach the mouth of El Nihuil and Salina. The objective for the creation of this reservation was the conservation of the wetland formed in the area and the preservation of its important fish richness, as there are found significant populations of Creole perch.
The vegetation on the adjacent land corresponds to jonquil and tupe grasslands in loose sandy soils.
There can also be found isolated low shrubs of chirriadera and male thyme.
Water birds are the representative fauna of the area, there are swans, vizcachas, hares of Castile, piches, partridges and rheas.