Abstract: Objective: To carry out bacteriological tests on the water quality of some streams in Cangshan Mountain, Dali, Yunnan Province, and to understand the effects of ecotourism on the water quality of streams. Methods: The samples were collected from the upstream and downstream of the Jade Belt Road, and the Yangnan Creek which is unfrequented by tourists, and the total number of colony, total coliforms and heat-resistant coliform bacteria in water samples were detected by plate colony counting method and multitube fermentation method. Results: The bacteriological indexes of the water samples below the Jade Belt Road were higher than that of water samples collected up the Road（total number of colonies: P = 0.014<0.05, total coliforms: P = 0.026<0.05, thermotolerant coliforms: P = 0.002<0.05）. The bacteriological indexes of all water samples in summer were higher than those in winter（total number of colonies: P = 0.007<0.05, total coliforms: P=0.001<0.05, total thermotolerant coliforms: P=0.020<0.05）. Jade Belt Road got higher bacteriological indicators than the Yangnan Creek. Conclusion: Ecotourism has an impact on the bacteriological index of Cangshan streams in Dali. Therefore, the development of ecotourism should pay attention to the possible public health problems. Public health and environmental protection departments should participate in the planning and implementation of ecotourism to ensure public health and safety.

Key words: ecotourism, Cangshan Mountain, streams, bacteriological indicators, public health