The lake is of volcanic origin and was formed by a large
basaltic lava flow from
Volcán de San Diego in the
San Diego volcanic field which blocked the Güija depression's original drainage. Lake Güija is fed by the Ostúa, Angue and Cusmapa rivers and is drained on its southeastern side by the río Desagüe, a tributary of the
río Lempa. The lake is surrounded by the volcanic cones of the Mita, San Diego and Cerro Quemado. The Salvadoran side of the lake has several small isles: Teotipa, Cerro de Tule and Iguatepec, where a substantial number of
pre-Columbian céramics have been discovered since excavations started in 1924.
Bosque San Diego La Barra lies on the eastern side of the lake.
World Heritage Status This site was added to the
UNESCO World Heritage Tentative List on September 21, 1992, in the Mixed (Cultural + Natural) category.
Important Bird Area The lake and its surrounds has been designated an
Important Bird Area (IBA) by
BirdLife International because it supports significant populations of range-restricted birds, including
white-bellied chachalacas,
orange-fronted parakeets,
Nutting's flycatchers and
white-throated magpie-jays. ==References==