The objective of this study was to investigate water quality and river utility among people settling along the Li River Lumphun Province. The study was designed by mixed methods. The number of sample size was 364 households in the communities. The research data were collected by questionnaires and analyzed by using descriptive statistics (SPSS for Windows version 19 ).The results showed that total water quality including DO BOD TCB FCB and NH3-N in the summer was at the moderate level (WQI 58 - 68). The Li River utility was at the moderate level (Mean = 2.73 S.D. = 0.57). The relationship between the water quality and the river utility for agriculture had a statistically significant correlation at 0.05 (p –value 0.04).

Tha Chin River is important to Samchuk Suphanburi province because the water can uses for urban agricultural tourism and industrial purpose. The increasing of population in Samchuk causes increasing of a demand of the water and a release of wastewater. Therefore the water quality of Tha Chin River was analyzed in flowing through Samchuk area in this research. The water sample was collected from seven ports area including two ports of urban area two ports of agricultural areas two ports of industrial areas and another port of tourism area. The water sample was monthly analyzed in various parameters including temperature in range 30-34 oC turbidity in range 28-59 cm pH in range 7.08-7.44 conductivity in range 19-23 s/cm dissolved oxygen in range 2.4-5.8 mg/L and biochemical oxygen demand (BOD) in range 2.0-8.4 mg/L depending on the seasons. In March exhibits the best water quality of Tha Chin River. In addition the water quality of Tha Chin River decreases from agricultural areas urban areas industrial areas to tourism area respectively. However the Tha chin river could be classified as class 1-3 which can be used for tap water fishery marine sport and agriculture.