Lake Kinneret (the Sea of Galilee) is a major freshwater resource in the water-scarce Eastern Mediterranean. Geochemical and biogeochemical processes in shallow shoreline groundwater influence the quantity and composition of nutrients entering the lake via lacustrine groundwater discharge (LGD), a component that remains poorly constrained in nutrient mass balances and lake ecosystem assessments. Fluctuations in lake and groundwater levels modify hydraulic gradients, thereby affecting LGD rates and water quality; however, the response of nutrient and salt discharge to these changes is not well understood. To investigate these processes, shallow (~1 m) monitoring wells were hand-dug along the shoreline near the Kinneret Limnological Institute. Groundwater was continuously monitored using in situ sensors (15-min intervals) measuring electrical conductivity, water level, temperature, dissolved oxygen, oxidation–reduction potential, and pH, complemented by biweekly water sampling. Samples were analyzed for major ions, trace elements, dissolved organic and inorganic carbon (DOC, DIC), δ¹³CDIC , alkalinity, and redox-sensitive species (NO₃⁻, NO₂⁻, NH₄⁺, Mn, Fe²⁺, HS⁻). Results indicate predominantly suboxic to anoxic conditions in nearshore groundwater, with redox intensity varying with distance from shore. More reducing conditions, characterized by active iron reduction, were observed closer to the lake, whereas wells nearer to land exhibited less reduced conditions and episodic nitrification. DIC, alkalinity, and δ¹³CDIC suggest that anaerobic organic matter oxidation dominates. PHREEQC modeling indicates carbonate mineral dissolution almost throughout lake-level ingression and regression cycles. These findings demonstrate that lake-level fluctuations significantly influence nearshore groundwater geochemistry and nutrient fluxes, with implications for freshwater lake nutrient dynamics.