The coastal mass balance for environmental tracers can be used to evaluate submarine groundwater discharge (SGD) and is often estimated using advective-dispersive cross-shelf transport models. Here we evaluate the sensitivity of different types of SGD tracers to key variables in this transport model under a wide range of environmental conditions. Salinity and long-lived radionuclides (here represented by Ra-226; half-life=1,600years) were transported by a combination of advection and dispersion under the scenarios considered, but short-lived radionuclides (here represented by Ra-224; half-life=3.66days) were mostly dispersed unless the offshore coefficient of solute dispersivity (K-x) was very low (<1m(2)/s). Sensitivity to variations in key transport variables was further evaluated by reinterpreting the cross-shelf trends in Ra activity in the semiarid Gulf St Vincent of South Australia (GSV). In GSV, the trends in most Ra isotopes (Ra-223, Ra-228, and Ra-226) in seawater could be explained similarly by a large number of parameter combinations, implying these tracers would provide highly uncertain SGD estimates in this environment. However, the range of possible parameter combinations was relatively smaller for Ra-224, suggesting that SGD estimates derived from this tracer would be most reliable for GSV. In both the sensitivity analysis and the reevaluation of the GSV data, K-x was the most sensitive parameter in the transport equation. Because K-x is an empirical parameter potentially encompassing different dispersion processes in time and space (tidal currents, storms, etc.), it is likely to be tracer, time, and site specific. Plain Language Summary Submarine groundwater discharge (or SGD) is the input of any water to the oceans that has been in recent contact with coastal aquifers, beaches, or the seafloor. Understanding SGD is important for the management of coastal waters because it can either bring new contaminants (like via the discharge of groundwater from septic systems) or recycle them when they are trapped in sediments (such as when waves push seawater in and out of beach sediments, bringing back nutrients from buried and decaying seagrass). Measuring SGD is difficult and is commonly made by using the chemical fingerprint created when water has been in recent contact with rocks and sediments. Our work describes how to better estimate SGD from trends in the chemical fingerprint in seawater. Because the fingerprinting chemicals persist in seawater for different amounts of time, they are impacted differently by the various processes involved in mixing coastal waters over time (like tides, storms, etc.). Thus, the mixing behavior in coastal waters for the SGD fingerprinting chemicals must be evaluated individually rather than by assuming that they will all behave similarly.