Variations in particulate matter, algae, and bacteria in an uncovered, finished‐drinking‐water reservoir

Physicochemical and microbiological analyses were performed on influent and effluent samples taken from Garvey Reservoir (Los Angeles County, Calif.)- Data collected on particle counts and size distributions, total plate count, coliform bacteria, algal counts, chlorophyll, turbidity, copper, and iron were analyzed with a computerized statistical package. The quality of the influent was degraded through biological activity in the reservoir to produce a lower-quality effluent. Results indicated that algae were associated with increased turbidity and particulate levels and might enhance or support bacterial activity, including physical protection of bacteria against the effects of chlorination. Although poorly understood, the physicochemical and microbiological implications of particulate matter in drinking water have become an increasingly important public health concern. A long history of aesthetic problems has been associated with suspended particles, but recently identified sanitary problems may prove to be more significant. Inorganic and organic suspended particles may protect viruses and bacteria from disinfection procedures1,2 or provide a suitable substratum for bacterial colonization.3 Algae can make up a significant segment of the suspended organic particulate matter in surface waters and have been shown to influence the numbers and types of bacteria in those waters.4'5 Algae are sometimes discounted as pathogenic agents; however, recent evidence has indicated that endotoxins associated