Formalist theories of knowledge that underpin GIS scholarship on integration neglect the importance and creativity of end-users in knowledge construction. This has practical consequences for the success of large distributed databases that contribute to spatial-data infrastructures. Spatial-data infrastructures depend on participation at local levels, such as counties and watersheds, and they must be developed to support feedback from local users. Looking carefully at the work of scientists in a watershed in Puget Sound, Washington, USA during the salmon crisis reveals that the work of these end-users articulates different worlds of knowledge. This view of the user is consonant with recent work in science and technology studies and research into computer-supported cooperative work. GIS theory will be enhanced when it makes room for these users and supports their practical work. ?? / Canadian Association of Geographers.