Laguna de Castillos

Comprising approximately 8,000 hectares, this lagoon, located in the department of Rocha, is unique in that its connection with the ocean is via a natural canal, the Valizas stream. It runs for 17 km and exhibits marked meanders, arcs of its primitive bed, with small islands in its tributaries. This creates a landscape of great beauty, with the added feature of the longest yearly connection with the ocean, with strong currents to and from the sea and frequent wind tides.


The lagoon’s main tributaries are the Arroyo Castillos, de Chafalote, de las Piedritas, del Consejo, Cañada de los Olivera and Arroyo Valizas itself.


Another unique feature of this lagoon is the sandy strip around a large portion of its coast, with a natural forest dominated by coronillas (Scutia buxifolia) and ombú (Phytolacca dioica). A significant part of the lagoon coastline is covered by reeds, which on the north coast are several hundred meters wide and form islands in the lagoon. It holds the largest ombú forest in the Rio de la Plata area. Also unusual are the palm groves, significant from the scenic point of view and also due to their singularity.

Importance for conservation

The area is home to a high diversity of endemic, threatened, restricted and charismatic species. Among the endemic species it is worth mentioning the Castillos annual fish (Austrolebias viarius) and the Valizas annual fish (Austrolebias cheradophilus).


Its singular beauty, a result among other factors of the unique vegetation occurring here like the ombú forests and the palm groves, this lagoon is singularly rich in avifauna. Several threatened species at the global level are regularly sighted here, among them the Dot-winged crake (Porzana spiloptera), Olrog’s gull (Larus atlanticus), the Black-and-white monjita (Xolmis dominicana) and the Saffron-cowled blackbird (Xanthopsar flavus). Near threatened species include the Greater Rhea (Rhea americana), the Chilean flamingo, (Phoenicopterus chilensis), the Bay-capped wren-spinetail (Spartonoica maluroides), the Buff-breasted sandpiper (Calidris subruficollis) and the Straight-billed Reedhaunter (Limnoctites rectirostris).

PH: Juca Gambarotta

Laguna de Castillos, a Protected Landscape

Laguna de Castillos was designated as a Refuge for Fauna by Decree 266/1966.  It was designated a UNESCO Biosphere Reserve “Bañados del Este”, and is also part of the Ramsar Site Bañados del Este y Franja Costera. It is also designated as an Important Bird and Biodiversity Area by BirdLife International under code UY020.


In February 2020 it was integrated into the National Protected Area System (Decree 059/020) under the category “Protected Landscape”. In this first stage, the protected area comprises two pieces of land owned by the State, the body of water of Laguna de Castillos and the body of water of Arroyo Valizas, from the bridge on Route 10 up to the lagoon.

Uses and economic activities


The area’s main economic activities are in connection with livestock breeding, artisanal fishing, tourism and in the past few years, forestry. As in Laguna de Rocha, land use in this watershed has shown changes which intensified as of 1996, which marked a sharp increase in forestry practices (currently a significant economic activity) and an expansion of agriculture.


Also in the past few years ecotourism has exhibited a strong growth, mainly in private lands.

The main threats


According to a study published by Vida Silvestre Uruguay in 2011, the following issues were recorded in the Lagoon area: overgrazing of natural pastures, wetlands, the ombú forest, the palm groves and forests in general; agricultural burnings to fight exotic species, and to “clean” “non-productive” land for grazing; invasions by exotic species; inadequate water management by drainage or effluents.


Other issues for concern are uncontrolled hunting o native species, mainly capybara; the introduction of high-impact productive models (forest monocultures, rice farming, monocultures of potato and soy); unregulated and uncontrolled tourist activities, and inadequate and insufficient waste management in the area in general and urban centres in particular (the towns of Castillos, Barra de Valizas and Aguas Dulces).