The citizen science based Waterwatch Program in the Mary River catchment in South East Queensland has successfully operated for 18 years.  This paper will discuss how the Waterwatch Program has evolved and been maintained and the role that the program plays in improving stream management in the catchment. The program has grown steadily and currently involves 112 volunteers who range from dairyfarmers, graziers, canegrowers, small croppers, park rangers, small business operators etc who monitor 126 sites. Involvement of community members in the Waterwatch Program allows for continual water quality observation and long–term data collection from public and private sites. Validity of data is assured through the implementation of regular training courses, workshops shadow testing and quality assurance guidelines developed by the Mary River Catchment Coordinating Committee (MRCCC) in conjunction with Queensland Department of Environment and Heritage (DEHP). Through comparing data with the water quality objective (WQO) guideline values, the MRCCC has developed a report card system to determine the health of individual Waterwatch sites and to produce Waterwatch reports that are shared with community members and local and state government agencies. These report cards and the underlying data facilitate higher levels of interest in water quality and better understanding of catchment management practices among the catchment community. The data has also been used for several purposes that contribute to improved stream management. These range from individual landholders identifying improvements or problems in their sub-catchment to the DEHP using the long-term data to verify and amend the current water quality objective guidelines. The MRCCC was involved in the initial preparation of the DEHP WQO's in 2005. The MRCCC thanks Gympie and Sunshine Coast Councils in particular for their ongoing support of Waterwatch.