Water Quality Index of Halda River, Southeastern Bangladesh

Water quality index was determined mathematically to assess the water quality of Halda River, a well-known spawning ground of Indian major carps and a tributary of the River Karnaphuli in south-eastern Bangladesh. Water quality and water quality indexes for seasonal and yearly were calculated from three selected stations situated upstream to downstream covering the entire fishing and spawning area by Weighted Arithmetic Water Quality Index method based on ten physicochemical parameters (Temperature, Transparency, TDS, Conductivity, pH, DO, BOD, Calcium, Total Hardness, and Total Alkalinity), analyzed monthly for two years, during January 2017 to December 2018. The Index classified the river water as good to poor during different seasons and annually. In the Station-1 (Nazirhat) upstream the water was good in monsoon, post-monsoon, and winter, but was poor during pre-monsoon. In the Station-2 (Satterghat) mid-stream, the water was good in pre-monsoon and winter andwas poor during monsoon and post-monsoon. In the Station-3 (Madunaghat) downstream, the water was poor for the entire four seasons. However, annually for two years, water was good in Stations 1 and 2 but was poor in Station-3. Index classified the water of Stations-1 and 2 as usable for domestic, irrigation, and industrial purposes, while the water of Station-3 is usable for irrigation and industrial uses only, and the river water is not fit for drinking without treatment. The level of all ten parameters was congenial for fishes in stations 1 and 2, whereas in Station-3 eight parameters excluding DO and BOD were suitable for fish. The study might help to create awareness among the users of river water for drinking and fisheries purposes and to keep the water in good condition.