En la búsqueda de variables que caractericen la calidad del agua utilizada con fines recreativos en las playas del dique San Roque, Córdoba, Argentina.

Surface water matrices are used for numerous recreational activities and as water sources for human, animal and irrigation consumption. The objective of the work was to select variables that characterize the water quality of beaches used for recreational purposes of the San Roque reservoir, Cordoba, Argentina. Three sites were evaluated: Bahia el Gitano (BEG, urban area), Perelli Beach and Club de Pescadores (PP and CP, non-urban area), between months of June/2013 and December/2015 (n = 96). For this, we analyzed: (i) physicochemical parameters: soluble reactive phosphorus, total phosphorus, pH, suspended solids, dissolved oxygen, ammonium, nitrites, nitrates, conductivity and water temperature; (ii) atmospheric: rainfall; (iii) microbiological: total coliforms (TC), fecal coliforms (FC) and viable enteroviruses (EV, whose detection meant the presence of at least 500 viral particles). The data matrix was studied through a multivariate analysis: principal component analysis (PCA), cluster analysis (CA) and multivariate analysis of variance (MANOVA). The highest values ​​of FC and TC were observed in BEG in wet months (p = 0.014 and p = 0.007 respectively) with 77% of the values ​​above the allowed limit. The EV was detected in 69.1% of the samples and was not correlated with FC, rainfall or beaches; which proves to be a robust indicator of fecal contamination of human origin with infectious capacity. The variables selected for the PCA were those whose correlation had a r> 0.5: conductivity, nitrates, nitrites, total phosphorus, suspended solids, TC and FC. The PCA (80.1% of the variance) allowed to select, according to the load of three components: nitrites, FC and total phosphorus as representative variables to characterize the monitoring. In CA with the variables selected for the PCA the similarity between two monitoring points (PP and CP) and the distance with the BEG beach were observed; whose statistical significance was demonstrated (MANOVA, Pillai p = 0.0012; Hotelling p <0.05). The selected variables could contribute to evaluate water quality since the pollution found on the beaches, particularly BEG in wet months, evidences the risk of exposure of population when performs recreational activities in this water matrix