WRRCTMR No.70 Stream Water Quality Assessment Based on Fecal, Coliform and Fecal Streptococcus Analysis

Abstract

The quality of stream water in Hawaii was determined by carefully analyzing samples of unpolluted streams, streams polluted with sewage effluent, sewage effluent, cesspool wastes, and storm drain runoff for concentrations of fecal coliform (FC), fecal streptococcus (FS), and selected physical and chemical tests. High concentrations (10^3-10^4/100 ml) of FC and FS could be recovered from samples of stream waters obtained from unpolluted and polluted sites. Most of the stream-water samples collected in urbanized areas, but upstream from the sewage effluent discharge site (unpolluted stream), contained higher concentrations of FC than the 200 to 400 FC/100 ml considered by state and federal laws as being polluted with fecal matter and as a possible source of enteric pathogens. Only after analyzing stream samples for concentrations and the ratio of FC and FS, as well as concentrations of phosphates, was it possible to determine which stream samples did or did not contain sewage effluent. The results show that the impact of sewage effluent discharge into streams on Oahu, Hawaii, cannot be properly evaluated by analyzing the stream samples for only FC as mandated by law. Moreover, it should no longer be assumed that stream-water quality upstream of the sewage effluent discharge point is superior to that of the effluent entering the stream. Conclusions should not be made based solely on measurements of stream samples taken downstream of the sewage effluent discharge site. To properly assess the impact of sewage effluent discharge streams, samples of the sewage effluent - as well as stream samples taken upstream and downstream of the effluent discharge site - should be analyzed for FC, FS, phosphorus, and turbidity.