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Levels of important biological and chemical water quality indicators in El Bordo. Gray dashed lines indicate detection thresholds (maxima or minima). Gray bar indicates the Mexican regulatory 30-day-mean water quality standard (NOM-003-SEMARNAT-2021). a. Total coliforms and E. coli at river (water quality standard is for E. coli) and frequent-use (f and h) sites. b-d. Nitrogen in ammonia, nitrites, and nitrates. e. Phosphate (orthophosphate). f. Total organic carbon (TOC).
