Laguna de Castillos

Laguna de Castillos was declared a Refuge for Fauna by decree 266 dated 1966, and will soon be designated as part of the National Protected Area System (SNAP, for its acronym in Spanish).

It covers approximately 8.000 hectares, and is part of the chain of coastal lagoons resulting from marine transgressions that took place during the Holocene. Unlike the rest of our coastal lagoons, Laguna de Castillos does not exhibit a sand barrier parallel to the coast but a canal (Arroyo Valizas). It is some 17km long and presents marked meanders, arches of its original bed, tributaries with a dendritic appearance and islands between them, which endows the area with a unique geography.

Of all our lagoons it is the one that stays open the longest, in this case the sandbar of the canal, and as well as the current from or towards the sea due to differences in the water levels, there are frequent wind tides.

One of its main characteristics is the sandy strip surrounding a large part of the perimeter of its coast, with a very interesting native forest. It is dominated by coronillas (Scutia buxifolia) and ombú (Phytolacca dioica), constituting the largest group of the second species in the country and possibly of its entire distribution. A significant part of the coast is covered by reeds, which in the north margin are several hundred meters wide and form islands that advance into the lagoon.

PH: Juca Gambarotta

A high diversity of fish is found here, especially noticeable for the mixture of fresh and salt water. Both saltwater and freshwater fish are captured by the community of fishermen located near the bridge over route 10.

Among them, we may mention bagre negro, el pejerrey y la tararira y entre las de agua salada la corvina blanca y el lenguado.

Other species with commercial value are the blue crab and the shrimp. The latter is growing in commercial relevance, and is extracted at the end of the summer and autumn. In the seasonal waterholes that border the fields adjacent to the lagoon there are at least 4 species of annual fish, among them Austrolebias viarius, endemic to a small area centered in Castillos.

15 species of amphibians, 36 mammals, 16 reptiles and 267 species of birds have been recorded in this lagoon, many of them of importance for conservation. This is also the case of the palma butiá which forms dense palmares in the area proposed for designation under SNAP.

To many, the great attraction in this lagoon is the ombú forest, but an indubitable complement to the traditional boat tour is the abundant birds that can be observed on the margins of the Arroyo Valizas. Black-necked swans are more easily viewed in the lagoon during the summer, when the marshes have less water or are dried out; but the coscoroba swans, while also more numerous in the summer, are easily seen all year round. The population of black-necked swans is between 1,000 and 1,400, but during the long drought of the year 2000 some 5,000 individuals were recorded. Coscoroba swans number between 300 and 700. However, the most abundant species is the cuervillo de cañada, when they congregate at their resting spots, and gallaretas.

Laguna Castillos plays a very important role as a refuge for birdlife, when tens of thousands of gallaretas are observed. During the 2015 drought, an estimated 40,000 were seen in the lagoon. Also, most of the species of ducks recorded in Uruguay have been observed here.

The lagoon and the ombú forest may be visited via three points:

Barra Grande: 099050631,
Guardia del Monte: 099872588

Monte Grande and DINAMA land (including a tour of the Valizas Canal): 099295177

Text: Juca Gambarotta