Groundwater transport of phosphorus (P) from the altered wetland soils of the Hula Valley may influence the water quality of Lake Kinneret, which provides up to 30% of the potable water for the state of Israel. This study was conducted to evaluate P mobility from the Hula's wetland soils to waterways under various hydrological conditions using a field-scale experiment (0.8 km2) with well-monitored boundary conditions. The spatio-temporal changes in hydraulic head across the study area were measured using automated monitoring stations installed in eight observation wells. The hydraulic conductivity (K) of the near-surface peat/marl layers (179 m d-1) was significantly larger than the K values (0.001 to 0.03 m d-1) measured in the marl layers at 5 to 15 m below surface. The large K values of the near-surface layers result from the drainage of this wetland in the late 1950s followed by the oxidation of the peat layers and dissection of the lower peat and upper silt-clayey marl layers. Using a simple water-budget approach, the large field experiment yielded a discharge of 0.27 Mm3 and a loading of 306 kg P transported from the altered peat soils to the waterways, in just 7 weeks. Most of the P loading was in the form of particulate P (> 0.45 µm) rather than dissolved P.