Groundwater can spend days to centuries in the ground before being discharged to streams. Once in surface waters, outgassing (evasion) might occur as groundwater equilibrates with the atmosphere or experiences pH shifts. Outgassing may also occur as surface waters interact with the surface ocean. Ultimately, the effects of enhanced weathering should be understood as an overall shift in CO₂ fluxes from the system as a result of the alkalinity introduced by rock weathering. Any changes in outgassing in the project scenario as compared to the counterfactual should be accounted for. The long timescale and large spatial scale of this process makes it difficult to study directly, but regional models could inform baseline- and project-scenario evasion estimates.