Water quality in the Sonora River: Summary and analysis of data from the Río Sonora Trust, 2014-2019

Abstract

Objective: Examine the water quality monitoring database of the Sonora River Trust during the period 2014-2019. Methodology: First, the values reported in the monitoring were compared with the maximum permitted limits of the current official standard, the WHO guide and the guidelines for the protection of aquatic life; then, the out-of-limit cases were summarized by site and month to have a spatiotemporal perspective of the database. Results: Serious absences of months without any sampling were found, even in the most critical periods after the spill; even so, the extraordinary presence of values outside the limit was confirmed in the period closest to the spill and the permanence of certain parameters in the years subsequent to the contingency. Limitations: Because it is a first approach to an already complete database, the groupings of parameters outside the limit that occurred in certain months and places were not analysed, without delving into all the possible toxicological risks. Value: High empirical merit for the study of the impacts of disasters of mining origin. Conclusions: The analysis of the trust database allows a global perspective of the impact on water quality of the Sonora River spill and, likewise, reveals the failures in disaster response, in terms of monitoring.