The Fitzroy basin in central Queensland is the largest basin in the Great Barrier Reef catchment area. The large quantities of sediment and nutrient export are of concern and come predominantly from diffuse sources in the grazing industry. The focus of the research reported in this paper was on the potential supply of mitigation actions from this group. This potential supply is very difficult to establish ex ante. However, such information may be crucial to the design of a quantity-based mechanism that requires supply of mitigation actions. In this study, the use of a stated preference technique called “choice modelling” and an experimental economics technique termed “experimental auctions” were applied to ascertain potential supply relationships.