After the eruption in the active crater of Rincón de la Vieja volcano, residents of Gavilán and Buenos Aires sectors of Upala reported a grayish color in the Pénjamo, Azul and Quebrada Azufrada rivers, at around 7 am on Thursday.
In Burma de Upala, residents reported the Niño River (located 15 km from the volcano) turned gray. This was accompanied by a small increase in the channel level, sulfur odor and slightly warmer water. Subsequently, large numbers of fish began to die.
According to the organization Volcanes Sin Fronteras, when analyzing the affected specimens, they concluded that they were species such as Brycon Costarricensis (machaca) and Astyanax Nicaraguensis (sardines). Their gills were burned.
In addition, a dead Caiman Crocodilus (caiman) was found on the riverbank.
Rincón de la Vieja volcano has been in a stage of intense phreatic activity since 2011, with fluctuating episodes of eruptions, and increased activity since the end of 2015.
When these explosions occurred, part of the lake that is acid came out of the active crater and fed the different streams, which caused a decrease in pH (makes them more acidic), increased turbidity due to the ejected ash, as well as an increase at its level and temperature.