Injected biomaterial could leak from the storage reservoir if the reservoir loses integrity and the biomaterial migrates, or if the biomaterial degrades and releases greenhouse gasses that escape the reservoir via the well head or surroundings. These risks are contingent upon the characteristics of the injected biomaterial (e.g. pH), the operation and maintenance of the well (e.g. pressure, temperature, and ultimate well capping), and the depth and geology of the storage reservoir. Monitoring for leakage will likely require a combination of direct measurements and modeling. This approach may be partially dictated by the relevant permitting authority (e.g. EPA UIC), but characterizing leakage risks is still an area of active research. Any GWP assumptions used to incorporate the leakage of non-CO₂ gasses into the calculation of net carbon removal should be transparently disclosed.