Departement of Environmental Engineering, Faculty of Civil, Environment and Geo Engineering, Institut Teknologi Sepuluh Nopember, Indonesia

Email: Lisaegunawan@gmail.com; irwan080565@gmail.com

Kali Buntung actually is a man-made afvoer river. However, due to city development, the location now become a strategic asset for Sidoarjo Region. Due to that reason, this river experience external forces such as rapid land conversion, social, law enforcement, upstream quality, rainfall and surrounding businesses that make the rivers’ burden much heavier. This paper aims to investigate the external forces matters and the calculating the impact of those external forces towards the water quality in Kali Buntung’s downstream area. Using Structural Equation Model (SEM) as the basis to produce such intended result, the indicator data will be processed using SMART PLS statistic software. The result of this research was favor law enforcement model. Eventhough facing another challenging factor such as social, upstream water quality and land conversion, law enforcement has proven to reduce the pollutant in Kali Buntung’s downstream, even surpass either the rainfall or business factors.