Urban wetland parks are a new type of urban park that have developed rapidly in recent years and have caught the attention of multiple governmental departments. The objective of this paper was to describe the trophic states of creeks and their relationship to water levels in an urban wetland park in Xixi, China. The study was based on temporal and spatial data collected monthly between March 2009 and March 2010. The results indicated that: (1) water quality significantly changed from upstream to downstream in study creeks. From upstream to downstream, water quality of creeks I and III improved; however, the water quality of creek IV and V declined; (2) trophic states in Xixi creeks differed according to seasons. Overall, the nutrition in creeks was measured at the slight eutrophication level. Nutrition was highest in summer and lowest in winter; (3) the relationship between water quality and water level differed dramatically between creeks. Water quality and water level in creek I was significantly negatively correlated, while no obvious trends were observed in other creeks. In order to improve water quality in creeks, the valid technique is to strengthen the management of inflowing water quality and then control water levels.