The present research investigated the relationship between nitrate-nitrogen (NO 3 -N) in river water and the land use/land cover (hereafter land use) in Teshio river watershed located in northern Hokkaido island to understand the effect of human activities such as agriculture, forestry, industry and urbanization in the drainage basin on the river ecosystem quality and services. River water was sampled at nine points seasonally during a two-year period and nutrients concentration was measured. Land use profiles were estimated at two spatial scales-riparian and sub-catchment for each sampling station. The spatial pattern of water quality in the Teshio River showed increased NO 3 -N levels associated with the agriculture and urban expansion, and forest reduction in the watershed. Land use at the riparian scale closely reflected that at the sub-catchment scale, which masked the unique riparian buffer effect on the river water condition. The high agricultural and reduced forest area in the riparian 2 zone, especially in the upper middle reach, could be a possible reason for the decline of ecosystem service for provisioning of clean water and habitat for aquatic organisms.Measures towards sustainable and more nature-friendly agricultural management are necessary in the area to protect the Teshio river ecosystem and its ecosystem services.