A bacterial water quality investigation of Canyon Lake, Arizona.

Abstract

A study was made on Canyon Lake to determine the source of fecal contamination and to learn how best to control the contributing sources. Of all the water samples taken from the Acacia swimming area, 5.5% exceeded the recommended standard of 200 fecal coliforms per 100 ml water. Bacterial levels determined for 24 sediment samples from the Acacia area were mostly in the thousands per 100 ml range. Fecal coliform-fecal streptococci ratios for both the water and sediment samples were predominately in the range where animal waste is the presumed source. A hypothesis is presented which implicates sediment-stored bacteria as the major immediate source of water pollution with human users and dogs as the ultimate sources. Bacterial survival data are presented showing how the fecal coliform-fecal streptococci ratio will shift with storage until, after one week, a ratio typical of human pollution will decrease to one indicative of contamination by animal wastes. Multiple regression analysis was employed to define the relationships between bacterial levels and site conditions and area use. User load index (car count) and/or turbidity were significantly correlated with fecal coliform count in most of the various regressions. This correlation over all data was about 50 percent.