Community data--where does the value lie? Assessing confidence limits of community collected water quality data.

Waterwatch is a national community-based monitoring network that aims to involve community groups and individuals in the protection and management of waterways. Waterwatch Victoria has the dual objectives of catchment education and water quality monitoring. The educational outcomes are evident, with the Waterwatch programme facilitating over 9,000 students to monitor more than 2,000 sites in waterways in 2000. This paper aims to assess the scientific value of community-collected data, through examining differences between Waterwatch data and professionally collected data. The study looked at all aspects of volunteer data collection, including data confidence protocols, equipment, and data analysis. All professional data was collated by the Victorian Water Quality Monitoring Network (VWQMN). The parameters examined in this study were turbidity, electrical conductivity (EC), pH and total phosphorus. The level of agreement between community-collected data and professional data varied temporally and spatially. Waterwatch data for EC and pH appeared to be very similar to professionally collected data. Equipment used by Waterwatch volunteers for turbidity and total phosphorus appeared to be limited in accuracy to moderate ranges. Overall the VWQMN professionally collected data showed less variance, suggesting greater variability, potentially due to inaccuracies, in volunteer collected data