The characteristics and abundance of reactive surfaces in aquifer media have long been recognized as key factors controlling the migration of contaminants and other dissolved constituents in groundwater. The authors have shown previously that the effective reactive surface area of a heterogeneous aquifer is a complex function of groundwater advective velocity and the correlation structures of the physical and chemical heterogeneities. Although in principle, the available surface area within an aquifer could be estimated using geostatistical techniques and laboratory BET surface area determination for individual samples, this approach is fraught with difficulties associated with inadequate sample coverage and lack of appropriate methods for scaling laboratory surface area measurements. An alternative approach (multiple-tracer approach) to the difficult process of estimating available aquifer surface area relies on the use of conservative and slightly reactive tracers to assess the integrated effective reactive surface area along flow paths. This multiple-tracer approach sacrifices detailed understanding of the fine-scale heterogeneity but can provide integrated large-scale estimates of effective reactive surface area useful for the prediction of reactive transport. The approach is demonstrated by the analysis of the breakthrough curves for paired tracers in heterogeneous media.