Abstract:
This study was conducted to evaluate the spatial and temporal variations in water quality of Rawai Lake which is subjected to various point and non-point sources ox pollutions like untreated domestic waste, poultry and animal waste and agricultural runoff. People living adjacent use this fake water both as surface and ground water thr drinking and domestic purposes. Eight standard water qualilY parameters were analyzed over a period of six months at six selected locations of Rawal Lake. Prior to sampling, a detailed survey of the lake was conducted to select sampling sites. The lake is being fed by Kurrang River and few other streams. The selected six sampling sites included the inlet of four major incoming streams, the outlet at the spillway and near the center or the lake. "\'he Global Positioning System (GPS) was used to mark the locations of the sampling sites.
The analysis of the samples showed that lake water is polluted with municipal waste and effluent from small businesses. it was observed that change in temperature affected the concentrations of DO and other physical and chemical parameters. "l'he chemical parameters were found mostly dependent on the change in influent loads in the lake and precipitation intensity. While during the dry season the organic load in the lake reduced, it increased considerably during the wet period. Similar affects on turbidity level, hardness and DO were also observed. Overall water condition of lake was found satisfactory. Randomly Iron, Manganese
and Arsenic were also observed but were föund to be well within the WHO •s guidelines. Bacteriologicaily, the water is contaminated with fecal coli form, hence, direct use of lake water for human and animal consumption is not recommended.
