Settlements that develop around rivers will result in problems with the disposal of household waste to the riverbanks. There is quite a lot of household waste that enters the river. This study aims to determine the pollution index of the tributaries of the Kahayan Mendawai 7 Palangka Raya River to the fish in the river. The analysis was carried out using water quality analysis based on the MPN (Most Probable Number) Coliform, consisting of three test stages, namely an estimation test using Lactose Broth (KL) medium, a confirmation test using Brilliant Green Lactose Broth (BGLBB) medium, and a certainty test. using Mac Concey Agar (MCA) medium. This type of research is a direct survey method and laboratory analysis. this research was carried out in October 2021. The results of this study were obtained based on the formula and table of MPN values, three series of tubes were obtained with the total MPN Cokiform value in the estimating test of 2,400 cells/100 ml sample, the MPN value confirming test 28 cells/100 ml sample, and the number of Escherichia coli colonies in the certainty test were 69 colonies, so the water quality of the tributary of the Kahayan Mendawai 7 Ujung City of Palangka Raya was in the category of polluted and unfit for consumption.