Yinfu Reservoir is an important source of water supply of Qingdao. The field investigation was conducted on this reservoir in the summer of 2010. Five sampling points were placed on the tributaries around the reservoir. Severn sampling sites in 3 layers (surface, middle layer, bottom) to take water samples were arranged. Monitoring objects include: T, pH, SD, TP, TN, Chl-a, salinity, TDS, conductivity. The spatial variations of water quality were analyzed. The results showed that the salinity, conductivity, TDS, TN concentrations of reservoir monitoring points around the tributaries were generally higher compared to the inner monitoring sites. The concentration of TN reached the Four water standards; little difference existed in the concentration of TP and DO, up to A water standard; the content of Chl-a in the outer monitoring points is lower than that of the inner. The content of total nitrogen in the surface and bottom of the reservoir was higher. The content of Chl-a is highest in the surface of reservoir; the content of suspended matter increased with water depths, however, no significant changes in conductivity and salinity with depth. The analysis of water quality data of years showed that the content of nitrogen in the reservoir is closely linked with rainfall. The content of total nitrogen in the dry season is always highest while the content of COD in the wet season is highest.
