The Kopai River, which is fed by seasonal rainfall, originates at the Chhotanagpur plateau's edge in Jamtara, Jharkhand, and flows northeast before joining the Bakreshwar River at Hansulibank in Birbhum, West Bengal. Together, they form the Kuya channel, a right bank tributary of the Mayurakshi River. As a fifth-order dendritic river, the Kopai traverses porous soil, rendering it vulnerable to seasonal floods and erosion. It spans an area of 505 km2, featuring a central channel of 112 km. This study aims to evaluate the nature, type, and, importantly, the effects of human activities on the Kopai River. It employs bibliographic history, analysis of topographical sheets from a Survey of India, and a review of chronological satellite images. Field visits and accurate measurements confirm the findings. The primary human impact on the Kopai River system has been the growth of brick kilns along both banks from 1970 to 2024. The first brick kiln was established in 1970, and more than 25 are currently in operation, although some have been abandoned. The river basin is significantly affected by the construction of bridges, barrages, and check dams. The degree and intensity of human alteration of the Kopai fluvial system leave various environmental marks. The transformation of the floodplain into agricultural land, dependent on the Kopai for irrigation, has further contributed to soil erosion and increased sedimentation in the river’s narrow path. Runoff from fertilizers and pesticides used in agriculture is a key factor in the degradation of the fluvial ecosystem and riparian vegetation.