The midstream of Blanakan is located between upstream and downstream. Due to its location, the water of the midstream receives pollutants from nearby upstream. Hence, the purpose of this research is to investigate the concentration of Zn and coliform in the midstream. Coliform is one of the standards used for assessing water quality. The samples were collected from three stations in midstream. The Zn in water samples was analyzed by using AAS. Meanwhile, the coliform was examined by MPN and plate count methods. The results of obtained coliform then compared with the river water quality standards issued by Government Regulation No. 82 of 2001. In the midstream of Blanakan, the ranges of coliform were 7.5 x 10⁻¹ MPN/ml, 9.3 x 10¹ MPN/ml, and 4.3 x 10⁻¹ MPN/ml. Meanwhile, the ranges of Zn contents were 0.45 mg/l, 1.53 mg/l and 0.5 mg/l. According to Government Regulation No. 82 of 2001, the limit of Zn is 0.05 mg/l, and the limit for coliform is 10 MPN/ml. To conclude, the Zn contents in water indicated that pollutants had influenced the midstream of Blanakan from domestic waste disposal from nearby upstream.

布拉纳坎的中游位于上游和下游之间。由于其位置，中游的水从附近的上游接收污染物。因此，本研究的目的是调查中游锌和大肠菌群的浓度。大肠菌群是用于评估水质的标准之一。样本是从中游的三个站点收集的。水样中的锌采用原子吸收光谱法进行分析。同时，通过MPN和平板计数法检测大肠菌群。然后将获得的大肠菌群结果与 2001 年第 82 号政府法规颁布的河流水质标准进行比较。在布拉纳坎中游，大肠菌群的范围为 7.5 x 10 ^-1 MPN/ml、9.3 x 10 ¹ MPN/ml , 和 4.3 x 10 ^-1MPN/毫升。同时，锌含量范围为0.45 mg/l、1.53 mg/l和0.5 mg/l。根据 2001 年第 82 号政府法规，锌的限量为 0.05 mg/l，大肠菌群的限量为 10 MPN/ml。总而言之，水中的锌含量表明污染物影响了布拉纳坎中游，来自附近上游的生活垃圾处理。