Evaluation of water quality in laguna Yuriria, Guanajuato, Mexico, by multivariate techniques: Valuation analysis for two times 2005, 2009-2010

Water quality assessment requires the use of statistical tools that facilitate the interpretation and taking of decision. The water quality indices has been promoted with the aim of contribute with water condition reports to society, while multivariate techniques, such as discriminant analysis (DA) are tools that enable the analysis of large number of samples and factors that allow the identification of sources of pollution affecting the water characteristics and offer a valuable and reliable tool for the management of water resources. This study is the result of water quality evaluations corresponding to two periods (2005 and 2009-2010), and aims to compare the water quality of Yuriria lake before and after the actions taken for restoration; for this, 21 parameters were analyzed including a water quality index and DA to determine the spatial and temporal variation of water quality. Our results show that the lake has a high level of eutrophication, with organic matter and fecal pollution; temporal variations in water quality were found, that manifest the effect of drought and rainy seasons. A severe drought in the second period was detected, which contributed to the concentration of nutrients and other parameters like total suspended solids provided by the tributaries. It was detected that La Cinta channel provides water of low quality and that the existence of villages are a determinant factor in space water quality variations. No recovery was observed in water quality between the study periods. The effects of drought can mask the effects of the strategies, actions and measures taken for the preservation and restoration of Yuriria lake, so different management actions at the basin level are suggested to allow a faster and efficient recovery of the aquatic environment.