Transition state (TS) localization calculations were performed using two complementary approaches to model the aqueous environment. The first incorporated both an explicit water molecule near reactive centers and a PCM solvation model. The second used only the PCM model, which approximates solvent effects through a continuous dielectric medium. This dual approach allows the evaluation of specific water-mediated mechanisms while maintaining a complete description of bulk solvation effects. The results involving explicit water molecules around the reaction are referred to as "water-catalyzed" throughout. The water-catalyzed reaction mechanism enables the transfer of one or several protons to or from water molecules in the TS and has a significant impact on the reaction energetics. From our analysis the explicit consideration of water is crucial to resolving the low-barrier reaction pathway (See SI Section 1, the presence of water decreases the barriers by an average of 9.2 kcal⸱mol -1 and 77% of the investigated reactions exhibit a barrier lowering when an explicit water molecule is included). Perhaps unsurprisingly, this widespread catalytic effect suggests water played a fundamental role in enabling prebiotic rTCA cycle chemistry. The presented free energies of activation represent the lowest values obtained from calculations that included and excluded explicit water molecules. The results are organized around the mechanisms of the uncatalyzed TCA cycle (Section 2.1), a comparison of these mechanisms with the major off-target pathways that were discovered and the existence of parallel fixation cycles (Section 2.2), and kinetic analysis of the resulting network of reaction pathways (Section 2.3).