Politicians, scientists, environmental activists and regular folk are all scrambling for answers as to why thousands of dead fish suddenly appeared this week beside the Santiago River in the municipality of Juanacatlán.
Locals says the incident, which occurred in the community of the Ex Hacienda de Zapotlanejo, could be new evidence of serious contamination in the river.
For decades, the Santiago deservedly earned the moniker as Mexico’s most polluted waterway.
Only a few weeks ago, Jalisco Governor Enrique Alfaro boasted that his administration had invested nearly $US250 million in measures to clean up the river, which runs from Lake Chapala, around the outskirts of metro Guadalajara and down to the Pacific Ocean. Most of that money was spent on the construction, expansion and modernization of 19 treatment plants to prevent raw sewage from being dumped into the river by industries and small communities.
According to Juanacatlán authorities, this is not the first time large numbers of fish have died en masse along the river, although they stressed it is not a regular occurrence.
In 2013, 2014 and 2022, thousands of dead fish appeared in Lake Cajititlan, the small body of water located in the municipality of Tlajomulco midway between Guadalajara and Chapala.
On those occasions, state authorities said seasonal temperature variations together with build up of algae, leading to a reduction in oxygen levels, was the cause, although some independent investigators believed contamination of the lake was a significant factor.