The river Kosi is a spring fed river of Indian Himalayan region which quenches the thirst of major population of Kumaon region. The model WASP (Water quality analysis simulation program)is a widely used model suggested by EPA that can help simulate the water quality processes in diverse water bodies as reservoirs, ponds, lakes river like surface water bodies. The analysis in the 4 major selected stations of the stretch for Dissolved Oxygen was found to be 4-11mg/l as measured value whereas simulated values ranged from 1 mg/l to 10mg/l at the origin of the river, whereas at the end point of the river the simulated and measured value ranged from 4mg/l-8mg/l , 6mg/l. The Dissolved oxygen in the water is very essential to estimate the water quality as it directly affects the aquatic life and also signifies the presence of organic matter as well as microorganisms in the water. The continuous variations in the DO levels are observed in the entire stretch. The probable reason is uneven rainfall, scattered population and terrain complexities of the region. The continuous and frequent merging of various springs into the main course river results in frequent fluctuations in the physicochemical parameters of the river. This study is an attempt to comparatively analyse the water quality of the only river of the region with the simulated values from model WASP and observed water quality from daily sampling from the water body.